


Quadratic Functions

by clio_jlh



Series: college ot4 [2]
Category: Teen Wolf (TV)
Genre: Alternate Universe - College/University, Alternate Universe - Human, Anal Sex, Birthday Sex, Blow Jobs, Bottom Derek, Cunnilingus, Dancing, Dirty Talk, Exhibitionism, Face-Fucking, Fingerfucking, Forced Orgasm, Gangbang, Hand Jobs, Humor, Kink Negotiation, Masturbation, Minor Allison Argent/Scott McCall, Multi, OT4, Pegging, Plot What Plot/Porn Without Plot, Polyamory, Quickies, Rimming, Roleplay, Romance, Sexual Fantasy, Strap-Ons, Teaching, Teasing, Triple Penetration, Voyeurism
Language: English
Status: Completed
Published: 2014-07-10
Updated: 2014-07-10
Packaged: 2018-02-08 05:52:43
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 21,738
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1929138
Author URL: https://archiveofourown.org/users/clio_jlh/pseuds/clio_jlh
Summary: <blockquote class="userstuff">
              <p>It started because when they asked Stiles what he wanted for his birthday he said, "Sex."  Which, being cash-strapped students, was something they could give him.  Planning for the rest of their birthdays, though—that took a little more doing.  (But it was still sex.  Sex all the way down.)</p>
            </blockquote>





	1. first

**Author's Note:**

> This is me FINALLY fulfilling a bunch of prompts and ideas I got before, during, and after the writing of Completing the Square. Thanks to nrem and didoxidate for the prompts for the first two chapters, and everyone who enjoyed a sort of thought-starter of the third chapter posted on tumblr a while back. The fourth chapter was mostly prompted by Beyoncé and is full of her songs.
> 
> The biggest thanks go to pinetreekate, who helped immensely in getting this to look like a story and not a series of things that happened one time, and for getting me past some last-minute concerns.

In the two months between when they hooked up at that party and when they went home for the holiday break, Lydia, Derek, Erica and Stiles figured out a few things together:

1\. They did not like threesomes, kind of at all. One-on-one time was great—essential, actually, for their relationship to keep humming—and being all together had to happen at least one night a week. But when there were just three of them it was like the missing person haunted them, and they felt unsettled. When it was Derek who was running behind, usually because he was stuck up in the chem labs waiting for something to happen, they sent him sexts and naked selfies of them in his bed but didn't touch each other (much) until he got back, flushed and hard and ready to fuck.

2\. Having the poly conversation with their parents was trickier than having the bi conversation had been. They all just seemed confused about "how does this work, exactly" as the Sheriff said. But then they had a big dinner, since it turned out Derek and Erica only lived a few towns away, and apparently seeing the four of them together just made it make sense for people.

3\. Their relationship started a completely insane rumor mill at their college which they did nothing to stop because they found it either insipid (Derek and Lydia) or hilarious (Stiles and Erica). Not that they could do much about it, anyway. Certainly it increased the listenership to Stiles and Erica's radio show, where they flirted and sent out dedications to Derek and Lydia who often worked together in Derek's office until it was over, and then Stiles drove them all back to Derek's.

4\. Their birthdays were all in a row in the spring, two before and two after the break. They planned to spend the break on campus anyway, because Derek had to work and neither Stiles nor Erica had the money to travel anyplace all that cool anyway. So Lydia worked on some project and Erica and Stiles basically took over the radio station. It was all good.

Planning for their birthdays, though—that took a little more doing.

* * *

It started because when they asked Stiles what he wanted for his birthday he said, "Sex." Which, being cash-strapped students, was something they could give him.

The night before his birthday, Stiles and Scott hit a small sports bar that wouldn't look too closely at their fake ID's. Allison's present was to play chauffeur, and she even dressed up for the occasion in a suit with brass buttons down the jacket and a hat. Allison had a lot of hats, and Stiles suspected the entire driving and outfit thing was just so she could wear one. Of course she looked super hot, because Allison Argent could rock some menswear.

Scott and Stiles mostly had pitchers of Bud because sure, there was a time to sit and sip whiskey and learn to like it, but that wasn't in a bar that was enough of a dive to be soft on underage drinking. Besides, cheap beer went better with extra spicy hot wings and mozzarella sticks. They mostly just goofed around, though Scott got sentimental at one point about something that happened when they were six and they had to hug it out. 

Stiles wasn't even that drunk when Allison dropped him off at Derek's place—drunk enough that he shouldn't be driving, sure, and he was a little more stumbly than usual, but he still knew his own _name_ , which was more than he could say for his birthday the year before. Maybe he really _was_ growing up, or something; he even remembered to chug a giant glass of water and take a couple of aspirin before he crashed.

* * *

It wasn't exactly tragic to be woken up at six-thirty, though it helped that it was a fresh-from-the-shower Derek doing the waking and that he was carrying one of his high-powered smoothies.

"Oh my god," Stiles said, making grabby hands. He slurped down a big gulp and could feel all the good things in the smoothie flowing into his bloodstream and making him feel a little more human. "Raspberry peanut butter, you are the best boyfriend ever."

"Happy birthday," Derek said, smiling, but also not quite making eye contact.

Stiles just kept sipping because Derek generally got there if you didn't rush him.

And after a few moments of silence he finally asked, "So, wanna fuck me before I head to class? I'm clean, obviously, and I got myself ready so you can just lie back—"

"I'm definitely not just lying back," Stiles replied, then sucked down the rest of the smoothie as fast as he could. "You arrange yourself however, and I'm going to brush my teeth and pee and come right back. Also?"

"Yeah?" Derek asked.

"Seriously you have to stop acting like asking me to fuck you is this huge request. I know I'm impatient sometimes but I _love_ fucking you. Okay?"

Derek took a deep breath, but he was nodding. "Okay."

Stiles didn't rush the brushing because under the layer of smoothie his mouth basically felt like the carpet on the floor of the jeep, ugh, and Derek deserved to kiss something nicer than that. By the time he returned to the bedroom, Derek had taken his boxers back off and was laying on his back, spread out in the middle of the bed. Stiles knew there would come a time when that sight didn't make him want to gasp, but he was glad they weren't there yet.

Derek had even gotten out the condom and insisted on rolling it onto Stiles and lubing it up himself, but after that Stiles took over, and Derek was pliant and gorgeous under him and so, so responsive. Stiles couldn't decide if his favorite part was the fucking, or watching Derek get fucked, or making him come, or coming himself. But it might have been laying in bed after, watching Derek get dressed, knowing that everyone up in the chem labs would be getting a blissful fucked-out Derek thanks to Stiles. He wasn't into marking his lovers—that was more Derek's thing—but he couldn't help feeling pretty damn proud of himself. Fucked-out was a good look on Derek.

And Stiles? He rolled over and went back to sleep.

* * *

By the time Erica showed up, a little after noon, Stiles was sitting on the couch in a t-shirt and boxers, building stuff in Minecraft. He was so not going to class on his birthday, no sirree. 

"Happy birthday," she said, plonking a bag on the coffee table. 

Stiles looked in the bag—chicken fingers and curly fries, nice—but Erica was walking right into the bedroom.

"What?" he asked.

She pulled her hair out of its bun and looked over her shoulder. "Wanna fuck me doggy-style in front of the mirror?" she asked.

He jumped up. "There's more than one answer to that question?" 

Erica was already out of her little dress and was kicking out of her shoes and slipping off her panties. "Want these? I have another pair around here someplace."

"Again, there's more than one answer?" He grabbed for them, but she moved her hand. 

"Kiss me first. I'm not _that_ easy."

He paused and looked at her.

"Okay, I am for _you_ , especially on your birthday, but I'd still like a kiss, please."

"Come here," he said, and laid one on her. She tasted like cinnamon gum.

"Thanks," she said, handing him the panties. Then she got on her hands and knees in the middle of the bed and wagged her ass at him as he went to the nightstand to get a condom. "Need some help?" 

"Give a man a minute!" But who was he kidding, really. It had been almost six hours since he'd fucked Derek, he hadn't masturbated since then, and here was his super hot blonde girlfriend begging for it. Her panties smelled awesome, too. They were so fucking wet, which gave him the bright idea to rub them against his hardening cock, and that totally did the trick. He tossed them down on the bed and knelt behind her. "Ready?" he asked.

"Do it," she said, bracing herself and smiling up at him in the mirror. 

He lined himself up and slid into her. "Wow, your tits look amazing like this."

"Yeah?" she asked, looking down at them still in her bright blue bra and then back up in the mirror. "Cool. Now what are you waiting for? Go, go, go!"

They went at it so fast that when they were done the chicken was still warm.

* * *

Stiles called his dad, and then spent the rest of the afternoon watching some baseball documentaries that Derek had recommended and dicking around on the internet. He was also vaguely wondering what Lydia was planning. She'd texted that she was bringing him dinner but what would the sex present be? Would there even be one? You could never be sure with Lydia, or at least, Stiles never was.

She came by before her evening class with salads. But she left them on the table and sat down on his lap.

"Hey," he said, putting his arms around her.

"Happy birthday," she said, and kissed him forcefully, her hands wrapped around his neck. She wiggled her ass in his lap and okay, so it was going to be like _that_.

Which was more than fine. He got off on her using him for her pleasure, and she knew it.

She pulled back. "Doesn't take much to get you ready, does it?"

"Not for you," he said. 

"Not for any of us, I've heard. At least today."

Because of course Erica had totally texted Lydia, or talked to her, or whatever. He wondered if they'd talked to Derek, too. "Is that a problem?" he asked.

"Not at the moment." She stood up and unceremoniously pulled out his cock, rolling on the condom that she'd had in her skirt pocket. Then she pushed off her panties and sat down on it. "No problem at all."

And he had to laugh at that, because it was so _Lydia_ , and far from the first time she'd done this. "You driving?" 

She nodded. "Just put your hands on my waist." 

But usually when she did this she closed her eyes, concentrated on what she was doing, was kind of selfish about it. Which was the whole point really, and Stiles _liked_ that. This time, though, she didn't take her eyes off him, not for a second. Her hands went from his shoulders to cupping his face, and it was so _intimate_ that he couldn't bring himself to say a single word. Even when he felt that he was going to come soon—and he _really_ wanted her to come first—it was all he could do to thrust up into her, as a little warning.

"It's okay," she whispered, smiling at him. "Come for me."

He did, his eyes opening wider, and she gritted her teeth and maybe she was coming, too, and it was … a lot.

They caught their breath, made out some more before Lydia slipped off him and put her panties back on. She handed him his salad, full of cheese and croutons, tossed with extra french dressing and therefore a little soggy, which was just how he liked it. She settled on the other end of the couch but kept her feet pressed up against his thigh, and he lay one arm down over her ankles. Lydia wasn't one to cuddle, especially after things got intense.

They ate in silence, quickly; Lydia had a class to get to, after all. When Stiles finished he caressed her ankle, affectionately. "So this has been a excellent birthday," he said.

Lydia laughed. "It's not over yet," she said. "You don't think there's going to be a big finish?"

"Really?" he asked. Because he'd hoped—was maybe hinting around for info a little bit there—but it had already been pretty great.

She looked at her reflection in the TV. "God, you've totally messed up my hair," she said, pulling it into a ponytail. 

Which, score one for Stilinski. 

Then she stood up and grabbed her bag. "Derek left something for you in the bathroom," she said, and kissed him before walking out the door.

"More presents for me," Stiles said. "Awesome!"

* * *

Sure enough there was a gift bag in the tiny linen closet and what was in it—well, after everyone wanting the D all day, it looked like the big finish was going to be Stiles getting seriously fucked. He wondered what the girls would be doing.

When Derek came back Stiles was still in the shower, because … ugh.

"All clean?" Derek asked, stripping and climbing in.

"There'd better be rimming in my future," Stiles said, poking him in the chest. "Because I popped a boner again using that thing."

Derek blinked at him, and then began running his hands gently along Stiles's arms, his go-to soothing maneuver, and Stiles went with it because _seriously_. "I'm sorry the douche still freaks you out. Thanks for using it."

Stiles shrugged. "It's polite, I guess. I just—what if it's like, the first step to becoming some giant enema freak?"

"Given how you're feeling right now, I think that's pretty unlikely. You were probably just thinking about getting fucked later."

"Yeah," Stiles said, sighing. "Thanks. Sorry, um, welcome home." He leaned in for a kiss.

"It's all right," Derek said. "Anyway, you like having things in your ass." He slipped one finger into Stiles's cleft, illustratively.

"Is that my present, things in my ass?" Stiles asked, leaning into Derek's hand.

Derek didn't give him an answer, of course. "Get out of the spray so I can clean up."

"I can help," Stiles replied, grabbing Derek's sponge as they traded places.

Once they were dry, Derek made good on his promise of rimming, laying Stiles out on the bed and using his fingers and tongue and a lot of lube. 

"Fisting?" Stiles asked.

"No," Derek said. "I wouldn't surprise you with that."

"But you want to?" Stiles asked, turning to look at him.

Derek paused, looking up and making eye contact. "We can work up to that, if you want to."

"Let's put it on the list," he replied. 

Stiles was quiet after that, except for the moaning and the "yesses" and the "fuck, right theres." He was floating out on a pretty great bliss stream, sinking bonelessly into the bed, when he heard the ladies come home. He was just about with it enough to turn his head toward the bedroom door.

Lydia and Erica were leaning in, all sexy conspiratorial smiles. "Got him ready?" Erica asked.

"Just about," Derek replied. Because he was a dick, he stroked Stiles's prostate with the tip of a finger, making Stiles moan and twitch.

"Fuck," Stiles said, and he wondered if he should be annoyed at Derek showing off his effect like this, and then decided he couldn't be bothered. It wasn't like the ladies didn't know.

"Good," Lydia said. "We're taking a shower."

"Can I watch?" Stiles asked. 

"No!" Erica said.

Which was okay because Stiles wasn't sure he could stand up all that well anyway. It was hard enough to move around on the bed as Derek wanted him to, but by the time Lydia and Erica returned, Stiles and Derek were leaning against the head of the bed, Stiles's back against Derek's chest. Erica was naked but Lydia had on a pair of boxer shorts that looked puffy and strange compared to her usual tiny lacy panties.

"All set?" Derek asked.

Erica nodded. "Ready for your present?" she asked.

"Yes?" Stiles replied, because of course, but also, he couldn't imagine what she and Lydia were grinning about.

Until Lydia dropped the boxers to reveal a strap-on. It was bright green, not upsettingly enormous but definitely big enough to get the job done, and it looked like it belonged, a natural contrast with her freckled skin. "Happy birthday," she said.

"Oh my god," Stiles said.

Erica lay on her back at the foot of the bed, and not for the first time Stiles was thankful they'd all chipped in to get Derek a bigger mattress. "Like it?"

"Yes!" Stiles's voice cracked, but he couldn't even be embarrassed about that.

"Good," Lydia said, kneeling between Erica's spread legs. "Wouldn't want all our practicing to go to waste."

"P-practice?" Stiles asked, because she couldn't possibly mean—but she did! She did, Lydia was totally pushing that strap-on into Erica's wet pussy. "Oh my god."

"I hope you don't mind," Erica said, her breath hitching just slightly as Lydia fucked her. "You know how Lydia is. She doesn't like to do anything unless she can do it well."

"It wouldn't be a present if there was _fumbling_ ," Lydia said. "We thought it would be okay if you watched."

"Totally okay," Stiles said. "Abso-fucking-lutely okay."

Stiles could feel Derek chuckling. "Also Erica makes the best lube."

"It's true," Erica said.

"Two birds and all," Lydia said. "And I think I got the hang of it, anyway."

"I would agree," Stiles said. His brain was still having trouble comprehending what was happening; he'd never spent much time watching pegging porn himself. Though now that he thought about it, Erica had shown him more than a few, both straight and lesbian, and he'd been appreciative. He just hadn't realized that was a _test of concept_.

Erica, interestingly, mostly just looked like she looked when she was getting fucked by Derek or by Stiles himself: happy to be along for the ride, one hand lazily stroking her clit while the other sat on the waist of her partner. 

"I can help with that," Stiles said. "If you want."

They both looked at him. "But it's your birthday," Lydia said.

"I'd like to."

He sat up, his body feeling a little more under his control than it had been earlier, and slid his legs around so that he was kneeling over Erica. But then he felt the absence of Derek, so he turned around. "You should, um ..."

"What, Stiles?" Derek asked. "What do you want?"

Stiles took a breath. It wasn't like he had a problem asking for things on a regular day, but he was a little overwhelmed, understandably. "Fingers?"

Derek smiled, but he was sitting up, too. "You mean, the part where you like having things in your ass?"

"Shut up," Stiles said, but he got what he wanted. Derek wrapped one arm around Stiles's waist as the fingers of his other hand worked slowly in and out, and it was all strangely comforting. 

Satisfied, he turned back to Erica and Lydia. He slid his left hand down her stomach to join her fingers at her clit, just above where Lydia was thrusting in and out. He could feel Derek's breath on his shoulder, and knew that his boyfriend was watching, too. 

"Go ahead," Erica said, relinquishing her clit to him, and he gladly took over, stroking it between his fingers the way he knew she liked. Up close he could see the shine of Erica's wetness on the dildo, the way it parted the folds of her skin. 

He turned to Lydia. "Can I ..."

"Sure," she said, nodding but not looking up.

He put his other hand on Lydia's back, relying on Derek to keep him upright and balanced, and moved it slowly down to the strap of the harness, just above the curves of her behind. Her hips were thrusting, steady, and it felt like when Derek fucked him, that easy rhythm.

"Do you like it?" Stiles asked. "Does it—can you come from it?"

"I haven't figured out how, yet," she said, sounding a little regretful. "But I still like it quite a lot." She grinned.

He smiled back. "Top."

"Bottom."

"Hey, who fucked who earlier?"

She turned to him and raised an eyebrow. "I'm going to let you think about that one."

"Close," Erica said, and they turned their attention back to her. Stiles moved his fingers faster against her and Lydia sped up, too. Erica was staring at Derek, just over Stiles's shoulder, which was smart—Derek could absolutely make you come just with his eyes. It was like, his superpower.

And come she did, moaning and muscles clenching, so fucking gorgeous the way she gave herself over to her orgasms, completely lost in it. Stiles always felt honored that she trusted them with that moment when nearly all of her walls came down.

"Mmm," she sighed, and turned to Stiles, smiling. "Your turn."

Lydia sat back on her haunches, the dildo sliding out of Erica easily, little trails of her wetness stretching out between.

Stiles licked his lips. "Next time you fuck her, I'm licking that thing clean."

"Not if I get to it first," Derek said. "Come on." He pulled his fingers out of Stiles and slid them both backwards to where they had been, backs up against the wall behind the bed. Then he put a hand behind each of Stiles's knees and spread his legs wide.

"Wow," Erica whispered.

Lydia showed no hesitation. "Ready?"

Stiles licked his lips. "So ready. Way fucking past ready."

She nodded and then she was lining herself up and pushing into him.

"Slow and steady," Derek said. "We've got all night."

"No no no no no," Stiles said. "No slow, why slow?"

Derek shook his head. "Don't listen to him. I don't."

"Cause you're a—" Stiles stopped, wincing at a sudden twinge of pain, but stubbornly refusing to cry out and show that Derek was right.

"She can't feel like I can, so try to be patient," Derek said, but he softened his words with a nuzzle into Stiles's neck and a kiss on the temple.

And so Stiles kept his mouth shut, relaxed and trusted in the process, even if they were getting there more slowly than he would have liked. Watching Lydia was a good reward, as concentration always made her look sexy but concentration on _sex_ was downright devastating. Erica loved seeing guys getting fucked anyway, so she was all over it. It should have made him feel self-conscious, with Derek spreading him wide open and everyone so focused on his asshole, but it felt too good for him to worry about it. Besides, it wasn't like they hasn't all already seen it, fingered it, kissed it, watched Derek fuck it. 

Eventually Lydia was buried in him up to the hilt. "All right?" she asked.

He nodded and put his hands on her ass. "Let's do this."

Lydia rocked back and forth, getting a rhythm going. It was different in plenty of ways—no balls slapping against his ass, smooth skin under his fingers instead of soft hair, the straps themselves—but it was also familiar: just getting fucked. Plus breasts, swinging in time with Lydia's thrusts, which was super hot, so Stiles cupped them in his hands. Lydia was so beautiful like this, so fucking perfect, like she was made to do this.

"Of course I was," Lydia replied.

So, okay, he'd said that part out loud, that was fine. But there was a little too much going on right now for him to talk, what with Derek strong and warm behind him, holding him open, and Lydia fucking him, hot and intense and _thorough_ , and Erica was right there behind her, a hand on Lydia's shoulder to keep her steady. He didn't want it to end but he also really wanted to come, so he reluctantly took one hand off Lydia's breast and reached for his cock.

"Let me do that," Erica said, which was also awesome because then they'd all be touching him, all helping him get off. Plus Erica would always reach between her legs to get her hand wet so she was like, jacking you off with her own come, and that was hot as fuck.

Hot enough that he wasn't going to last much longer. When he felt the orgasm coming he focused on not squishing Lydia's breasts, though he'd been teased enough that he didn't have that much strength left, and just flopped backwards, breathless.

Lydia pulled out and took off the harness, a little of Stiles's come on her stomach. He was glad that Derek had insisted on cleanliness, because he didn't want Lydia to be grossed out at all. He wanted her to do this again and again and _again_ , to do it to Derek, too, while he watched. Then he thought of something.

"Did you come?" he asked her.

"It felt good, I liked it, and orgasms aren't everything," she said.

"Bullshit," he replied. "I didn't make you come."

"It's not the same and you know it."

" _Lydia_ ," he said, because she knew, she _knew_ how he felt about making sure everyone came. He always kept track, especially when all four of them were together. It was _important_ to him.

"Derek hasn't come yet," she said.

"Derek is going to do what he always does when he spends an hour rimming me and making me crazy and then gets me off: he's going to pick me up and fuck me like I'm a rag doll, and it's going to be super hot and I'm going to wish that I could come again," Stiles said. "Or maybe I will; it just hasn't happened yet. Now back to you."

"I got close, I just—it didn't get me off," she said shrugging. "Now I feel overstimulated."

Stiles felt like all the air left his body. "Really?" he asked.

"What?" Lydia asked. 

"Yeah, so," Erica said, "as the person who watches porn with Stiles? I should tell you that he's pretty into forced orgasms."

"Not that I would ever force you," Stiles said. "Any of you."

Erica nodded. "And Lydia, I know from when we practiced with the strap-on this week that you got fidgety and weird after we fucked and I ended up going down on you anyway."

Lydia turned to her. "Tonight is supposed to be about Stiles."

"And Stiles wants you to come. Fake protests a bonus."

"Fake being forced?" She cocked her head. "Well, if you put it that way. Two birds, right?"

"Yes!" Stiles said.

Erica flipped off the bed and grabbed the big vibrator out of the nightstand drawer.

"Now that that's settled," Derek said, and pulled Stiles up, lifting him at the hips and thrusting into him easily, because he was so loose and lubed up. 

Stiles let his body fall back against Derek, wrapped his arms around Derek's neck and settled in for a good pounding. "Fucking love this," he said. "Even better after Lydia."

"Yeah," Derek said, breathless. 

"We should do this every time she fucks me."

"What makes you think I'm going to fuck you again?" Lydia asked, as Erica switched on the vibrator and knelt behind her.

"You fucking loved it," Stiles said.

Erica was whispering in Lydia's ear, putting the vibrator right on her clit without much warning, and Lydia flinched away from it. Somewhere in his brain Stiles knew that in those whispers Erica was coaching Lydia on how the girls in the forced orgasm videos acted, but that was fine with him, that they were faking this for him. Better, actually.

"No," Lydia protested.

"But Stiles wants you to come, so you're going to come," Erica said, holding her tighter, chin over her shoulder. 

Lydia moaned through gritted teeth.

"See? Your body wants to come. Just let it happen."

Lydia slapped at Erica ineffectively, but her shoulders were pushing back into Erica as her hips thrust into the vibrator.

Stiles was feeling pushed around, too, manhandled by Derek into just the right place, and so fucking turned on even though he was only about half hard. Maybe Lydia had a point about orgasms, but it was his birthday and he wanted to make everyone come, directly or indirectly.

Lydia opened her eyes and looked at Stiles, who thought he probably made a pretty picture all fucked out and draped over Derek. He smiled at her and he could just see her relax, and then she was coming. 

Derek, too, by the way he was pulling Stiles against him, hard. Maybe Lydia could also make people come with her eyes. They'd have to try that out.

Stiles sensed rather than saw Erica get off the bed, probably to get the toys into the sink, and then she was back with some wet cloths to keep them all from getting too sticky. Then she joined them on the bed, which was just about big enough for all of them if they arranged themselves right, a little overlapping, but that was kind of what they wanted.

"So, was it a good birthday?" Erica asked.

"Fuck yeah," Stiles said. "But it's not over yet. Not until Lydia fucks Derek with that gorgeous strap-on."

"I can do that," Lydia said. "If he's willing."

"Willing," Derek said, snuggling against Stiles. "Give me twenty minutes and I'll also be able."

"Good suggestion," Erica said, grinning. "Because that's going to be hot as hell."

"You know it," Stiles said.

"How are we going to top this for Lydia?" Derek asked.

Lydia laughed, low and a little evil. "Oh, I have some ideas," she said.


	2. inside

After the literally hours of sex for Stiles's birthday (and good thing his birthday was on a Thursday because on Friday she could barely move) Lydia knew that she didn't want to have another sex marathon for her birthday. 

Not that she hadn't gotten anything out of it. She'd fucked all three of her lovers with her new strap-on, one after the other. No, her cock—Erica had suggested she call it that and Derek and Stiles agreed with enthusiasm, so cock it was. She'd started playing with it on her own, too, pressing it against her clit in a way she couldn't quite manage when she was actually fucking someone else. And she'd used it a few times in the three weeks since Stiles's birthday night, getting better with the practice.

She'd seen the cock initially as a means to an end—she wanted to fuck Stiles, Erica and Derek agreed it was a fun idea for his birthday sex request, and so a cock was needed—but the more she wore it, the more it felt like her. As Stiles had said, maybe she was meant to have it. Fucking into something hot and wet and tight and seeing the other person shudder at the penetration was hot; she got why guys liked doing it. Erica liked it when Lydia wore it under her skirt, though so far she'd only dared to wear it down the two flights of stairs between her floor and Erica's, not, say, walking across the quad. It gave her a whole new way to top, and she liked topping, liked controlling what was going on around her. Happily her lovers liked her that way, too.

Of course, she could top with her pussy just fine, thank you very much. And that's what she intended to do on her birthday: not a marathon, but a very pleasant walk in the park.

* * *

When she was a kid, her mother had always made sure they did some sort of volunteering or service near her birthday, giving back in exchange for all the stuff she got. Most of the time they were things she would benefit from anyway, like helping to plant flowers in the beds of the divided main street downtown. Surely she could think of something that would be like a gift to her _and_ benefit her three lovers at the same time.

She was having a usual Tuesday, about to give Erica her post-tutoring reward for a flawless problem set. She'd already gotten rid of Erica's wet panties, though not before licking them while they were still on because that got Erica going like anything, and was getting ready to feast on all that flushed, wet flesh when Erica spoke.

"Has Derek ever gone down on you?" she asked.

Lydia looked up, a little annoyed that Erica was thinking about someone else while Lydia was giving her head, even if that someone was also dating Lydia. "Only once," she said, and went back to it.

But Erica was still talking. "Right? He's kind of terrible at it."

"Erica, really?" Lydia asked, sitting back on her haunches. She certainly wasn't going to do anything that wasn't the focus of Erica's attention; she had enough of that with Stiles.

"It almost hurts. That's why I had him stop doing it."

"Stupid Kate," Lydia said, and Erica nodded. Lydia didn't generally go in much for vilifying ex-girlfriends, or any women really, but Kate had earned her enmity by leaving Derek with a pile of relationship neuroses that she, Stiles and Erica had been painstakingly unpacking for a few months now. 

Erica was scowling, the way she did when she was trying to think something through, and Lydia made a mental note that in future she needed to make sure that Erica's thinking cap was turned off before any rewards were given. "It's just odd because he's so gentle most of the time, unless you don't want him to be."

"He _is_ very good at taking direction," Lydia said, and then she paused. "Which means ..."

"Lydia?" Erica asked, suspicious.

Lydia put on her most ingratiating smile—not that it often worked on Erica, but it was best to try. "I think I know what I want to do for my birthday. But I'll need your help, and Stiles's too."

Erica leaned forward. "What do you have in mind?" she asked.

"Do you want to know before or after your orgasm?" Lydia asked, raising her eyebrows.

"Oh, after," Erica said, eyes widening as she realized that her questions had been depriving her of Lydia going down on her, which, please. "Sorry, definitely after. It'll make excellent pillow talk." She nudged Lydia's knee with a pointed toe. "Or you can tell me all about it while I'm reciprocating."

"Let's focus on one thing at a time, shall we?" Lydia said. 

"Please, continue," Erica said, waving her hand.

Lydia went back to her original task, since after all Erica had earned it fair and square. If it also worked as a bribe to help with Lydia's birthday plans, so much the better.

* * *

On the day, Lydia borrowed Derek's car and she and Allison went shopping. She had a Macy's gift card from her parents and she was going to spend some of it on new bedding. The boys absolutely did not change the sheets often enough so she needed to take away not wanting to do laundry as an excuse. Besides, they deserved something pretty and soft. 

She thought of getting everyone sexy underwear but that felt too wifely and while she and Derek played those games sometimes, they were _games_ and not the reality of what she was doing with a gift card. She did buy towels, though, because they took a lot of showers at Derek's place.

Also some candles.

And some killer shoes, but those were just for her.

They went out to dinner that night at the nicer Vietnamese place, all six of them around a big table eating spring rolls wrapped in lettuce and mint followed by big bowls of pho. Ice cream came after, where Stiles and Erica proceeded to be so exaggeratedly erotic with their cones that Derek scowled and huffed, Scott and Allison dissolved into giggles, and Lydia was just glad that there weren't any uptight parents in the vicinity. Of course they were doing it on purpose, because they were in on what was about to happen and they liked to push things, but Lydia wasn't taking the bait. 

But Derek, for all his performative annoyance, couldn't take his eyes off them. It was kind of adorable, actually.

* * *

Back at his place, watching as Stiles lit the scattered candles and Erica adjusted the pillows on the bed, Derek started to get an inkling that something was up.

"Is there a plan that I don't know about?" he asked.

Lydia sat down at the foot of the bed and patted the spot next to her. He sat and put an arm around her, which was good; touch tended to keep him calm. She put her hand on his thigh.

"Who taught you how to go down on a girl?" Lydia asked him.

"Um, Kate, why?"

"Ugh, of _course_ it was her," Stiles said, rolling her eyes.

"Not helping!" Lydia said.

"Why?" Derek asked. "Is there—there's something wrong, isn't there?" 

Lydia shook her head. "I'll give her the benefit of the doubt that she honestly did want you to ... do what you do?"

"But?"

"Oh honey. Cunnilingus isn't just aggressive clit-licking."

"Oh," Derek said, and looked away, cheeks heating up with embarrassment. Lydia took his hand, but he wasn't looking back at her.

"It's weird," Stiles said, flopping down onto the bed behind them, "because you are _so good_ at rimming."

"So good," Erica agreed.

"And sucking cock," Stiles went on.

"Sucking tits," Erica said.

"Sucking balls."

"Licking me all over generally."

"Kissing."

"Five stars, would kiss again."

Derek said, "Okay, okay, I get it," but he was smiling a little, back with them. It really did take all of them, sometimes. "So, are you going to show me, or something?"

"On Erica," Lydia said, nodding. "Stiles will show you, since I've already trained him."

Derek turned to Stiles. "Trained?"

"Yeah, so you know that film class we're taking together?" Stiles asked. "We go back to her room after the screening and she reads that week's chapter out loud while I service her." He waggled his tongue in his mouth, then grinned. "Sometimes she sits at her desk and I sit under it, which is super hot. It's like those videos where the girls are reading with a vibrator in their pussy, because if I'm good I can distract her."

"And you aren't distracted?" Derek asked, raising his eyebrows. 

"Well, she quizzes me after, so I have to get all the questions right to get a blowie."

"It's pretty damn effective," Erica said.

Derek was quick enough to pick up that Erica meant Lydia did it with both of them, and cocked his head at Lydia. "You know you can't reward all your students with oral sex."

"No, just the ones in this room," she said, grinning.

"So I'll get a blow job for doing well?"

"Indeed."

"And how is this a present for you?"

"Uh, duh, Derek," Erica said. "We get you going down on us on the regular."

"Also she loves telling people what to do," Stiles said.

" _Actually_ ," Lydia said, "I'm just paying it forward. I'll be able to send you off into the world with improved life skills."

"What if how you like it is just as weird to someone else as how Kate liked it is to you?"

"And Erica. Plus I checked with Allison."

"Oh my god," Derek said, putting his head in his hand. "You _told_ her?"

"Of course I didn't use your name! But I suspected it was Kate and I wanted to make sure it didn't run in the family, for her own sake! I just asked Allison what she liked. I mentioned your technique, but I'm pretty sure she thought I was talking about Jackson, you know, my high school ex? Kira and Braeden were there, too, so that's five women's opinions."

Erica opened her mouth, probably to add to the list, so Lydia quickly shook her head. Derek did not need to know that they'd discussed oral sex technique with his little sister and his cousin. That would derail the entire evening.

"Okay, so, what do you want me to do?" Derek asked.

"You know what time it is, Stiles?" Erica asked.

"Is it naked time?"

"It's naked time!" she replied, and pulled her dress off over her head.

"Yes, that would be the next thing to do," Lydia said, but as her hands went to the buttons on her shirt, Derek stopped her. 

"Let me," he said, and she nodded. He kissed her as he removed her top and bra and she gave herself over to him, to their kiss. He pulled her up on her knees and she felt Erica's much smaller hands getting rid of her skirt and panties. 

She opened her eyes, breathless, and saw that Stiles had been doing the same for Derek; he was naked too, his hands still on her shoulders, his eyes unsure. 

"Five stars," she said. "Would kiss again."

He smiled.

"All right," she said, getting up. "Erica, sit where I am now. You two, on the floor in front of her."

Erica tossed a couple of pillows to Lydia, who placed them on the floor for Stiles and Derek, then sat down in the small chair behind them. Once they arranged themselves as she had directed, they looked to her.

She realized, then, that she didn't actually want to control this minute by minute but rather, cause it to happen, and watch. The idea of seeing how Stiles did when left to his own devices—and she knew he could dirty talk with the best of them—was already making her wet. "Go ahead, Stiles," she said, nodding. "You know what to do."

"Um, okay," he said, blinking, and then turned to Derek. "One of the awesome things about Erica is that she's like, super responsive, right? So she's basically going to let you know how she feels about what you're doing a second after you've done it."

"Pretty much," Erica said, grinning at Lydia. She was sitting up, leaning back on her hands, and her legs were spread wide. Of course Erica, the little exhibitionist, had happily agreed to being the test girl for Derek to learn on, once Lydia assured her that she'd be watching the entire time. She was showing off a little, thrusting out her chest, and Lydia had to smile at her. She was always happy to be the private audience for one of Erica's little shows. And if Erica exaggerated her reactions for Lydia's benefit? So much the better for Stiles the teacher and Derek the student.

"So anyway, this is how I usually start," Stiles continued.

Lydia sat back in her chair and let the words wash over her. Hearing Stiles translating her instructions to him into a step-by-step clinic for Derek was more of a rush than she'd expected. His dirty talk was incredibly explicit but no less sexy for that, and Derek's questions were thoughtful, considered, focused on what Lydia and Erica wanted. That was the audio part of the show; the visual was watching Erica's reactions as she was slowly driven crazy by Stiles and Derek. Slow being the operative word, because while Erica usually liked it fast and a little rough, Stiles's instruction and Derek's hesitation led the boys to take their time to get it right. 

"You want to—Erica, babe, can you spread your legs a little further for me?" Stiles asked, and nodded when she complied, though she needed to lean back on her elbows to do so. "Cool, thanks. Okay so just cup your hand sideways above her clit, there, and then use your thumb and fingers to spread her open. Now, Erica is a get-down-to-business girl; maybe a little warm up but she mostly wants you to just go directly to her clit, do not pass Go, do not collect $200."

"Hey," Erica said, scowling. "My clit isn't _jail_ , Stilinski."

"Sorry, didn't mean to imply," Stiles said. "Anyway, Derek, you probably already noticed that from feeling her up."

Derek nodded, his eyes glancing back and forth between Erica's pussy and Stiles.

"But Lydia wants you to hit every single inch of that real estate. You'd better get your tongue into every crevasse, along every ridge, before you even think about using your fingers or anything else. And believe me, she will notice if you missed a spot. I start on the outside and work my way in, but, you know, whatever works for you to keep track."

Lydia could almost see the wheels in Derek's head turning, and then he leaned in, tongue extended.

"Like I said, don't point it too much," Stiles corrected, but his tone was gentle, his hand brushing soothing circles on Derek's lower back. "That's good for rimming but not so much for eating pussy. Wow, underside, nice."

Erica hummed, letting her head fall back. Stiles glanced up at her, amused, and fondled her ankle.

"Okay, do it again, but make your tongue even softer. Here." Stiles turned Derek's head toward him and kissed him, open-mouthed, letting their tongues brush against each other. "Like that."

Derek went back to it, not quite as slowly as the first time, but still deliberate in his actions. Erica moaned, her leg twitching in Stiles's loose grasp, but he held her open. 

"Good. Again."

Erica huffed in frustration, but said no more. Usually she would have long since grabbed the head of whoever was giving her head and made her point by thrusting her pussy into their mouth. But now she was going with the process, Lydia suspected for her sake, as when Erica's eyes were open they were on Lydia, not the boys. Lydia smiled at her and pinched her own nipples with her fingertips, an uncommon bit of exhibitionism on her part but the best way she could think of to reward Erica under their current circumstances. Lydia was getting wetter by the minute, but unlike Erica she was patient enough to let this go, let the clench of lust in her belly go unsatisfied for now. 

"We might be ready to go inside. But remember—"

"Soft tongue?" Derek asked, and Lydia felt a little spike of pride that went straight to her pussy. She was beginning to understand why Derek had warned her that she couldn't reward all her students this way, because it was a heady thing. Or really, a bodily thing. She tried not to rub her legs together, and instead spread her knees a little wider in the chair, getting a little air on her pussy to slow things down for herself.

Meanwhile Stiles was grinning at Derek's question. "That's right. Don't fuck her with it. Neither of them like that. Lydia wants you to feel her up with your tongue down her throat _or_ eat her out but not both. Erica likes your lips on her clit and your fingers on her G-spot, but we'll do that later. Lydia's way is up first. So, soft tongue."

Erica was pouting now, knowing that she was a little further from climax. Her skin was flushed and covered in a thin sheen of sweat and as Derek slowly licked into her pussy Lydia could see her body lose its frustrated tension and come out the other side. She'd heard Erica call it "floaty," that place she rarely had the patience to let any of them take her, but her breathing was slowing now, her legs falling off to the sides, and she let go with her arms and lay flat on the bed. Lydia made a mental note to take it slow with Erica a little more often. Being driven crazy looked awfully good on her, and watching it felt good to Lydia, that she was the cause of that, even if indirectly.

"Give her a pillow, would you, Stiles?" Lydia asked, managing to keep her voice level. 

He quickly complied, still keeping one eye on Derek, but Derek noted the absence and sat back.

"Have you ever," he began, then stopped.

Stiles and Lydia waited, Stiles absently stroking Erica's pussy with his thumb, no doubt to keep her humming. 

"Have you ever gotten her G-spot with your tongue?" Derek asked.

Stiles cocked his head. "Well, I mean, Erica wouldn't let you because she wants fingers, and Lydia's is kind of hard to find if she isn't super turned on." He gestured in the air with two crooked fingers. "Also it's pretty far up there. Maybe if you had a lizard tongue or something."

Lydia realized that he'd been _remembering where her G-spot was with his fingers in the air_ but instead of finding it ridiculous—which she should have; it was entirely ridiculous—she shuddered to think that he knew her so well, that his fingers knew her body from sense memory. She was glad that Erica was too out of it and Derek and Stiles too focused on the task at hand to see her reaction; she wasn't sure she was ready for them to know how it affected her.

"Maybe I could try with Erica?" Derek asked.

"Do it," Stiles said.

Derek leaned in again, a determined set to his shoulders, and went to work. It took a minute or so, time that Erica seemed to thoroughly enjoy from the way her head rolled back and forth. Then he must have found it, as suddenly Erica arched her back and grasped the sheets, moaning shamelessly. 

Pretty a picture as she made, Lydia didn't want her tearing the new bed linens. Besides, Erica had taken one for the team long enough. "Get that girl off before she strains something."

Stiles turned to her, blinking. "Oh, yeah, sure," he said, and then to Derek: "To come, she needs fingers." He thrust two long fingers into where her pussy was so wet and flushed, and placed his own soft lips and tongue just above her entrance.

Derek nodded. "G-spot and clit, I know."

Erica reacted as predicted, shouting as she came, her muscles contracting, but she only rested for a second before she said, "Again!"

"You heard the lady," Stiles said.

This time it was Derek's turn to quickly finger-fuck her and tongue-kiss her clit, going straight to those sensitive places, because sometimes Erica needed to go twice, or even three times, before she felt sated. 

Though given how she lay bonelessly on the bed, two looked like enough. Lydia felt transfixed, rooted to the spot by Erica's shamelessness. 

"Good?" Stiles asked, and Erica could only nod.

Stiles nodded, and put a hand on Derek's shoulder. "Young Padawan, I have taught you all that I know." Stiles kissed him, ignoring that he was rolling his eyes, then turned his shoulders so he was facing Lydia. "Go get her."

Derek walked on his knees to her. "Do you want to move to the bed?"

Lydia blinked, trying to shift gears as quickly as they had. She cleared her throat. "No, actually. I like the chair."

He nodded, and seemed to be assessing the situation; she felt _known_ again, and bit her lip. "Do you need a break?" he asked.

"No," she said. "I mean, I don't want one."

"Okay," he replied. Then, quickly, he lifted her legs over his shoulders.

She slid down in the chair but he had her, his hands cupping her ass to spread her even wider, and while the position should have been precarious, she felt secure in his arms. 

"Comfortable?" he asked.

"Yes, I'm—it's fine."

"It's a good angle, I think." He smiled at her, and then tipped his head down and dove in.

It was evident from the first brush of his lips that he'd been taking careful mental notes. Lydia did her best to be as responsive as Erica, and to remember what Stiles had been telling him, but she was too hot from the show they'd put on for her to be able to think about what was happening. She was in the feeling place now, her eyes on the top of Derek's head, her body literally in the palm of his hands. She sighed, relaxing further, but he still held her easily.

Derek was slightly awkward but in no way hesitant, apparently uninterested in giving her the slow burn he and Stiles gave to Erica. Which was fine with Lydia; she'd been thinking about this and watching for long enough, and she was certainly wetter and more open to start with than usual. His beard was soft against the skin of her inner thighs and he kept humming, vibrating against her skin, which was _not_ something he'd picked up from Stiles. She enjoyed the contrast, getting something a little different than what either Stiles or Erica might do. Her body started to vibrate in sync with his.

Then she realized he'd be even better next time, and every time after that, because that was who Derek was: a refiner, a perfecter of technique, a scientist. The efficiency in getting her going that he was currently demonstrating meant she could stop by his lab in the middle of the day for some under-the-skirt action. It was the thought of that, of him on his knees in his tiny office with her perched on the edge of his desk, that sent her over the edge. His strong hands held her fast, keeping her from clenching her thighs around him but also letting her thrash all she wanted. 

When she opened her eyes he'd pulled back and was carefully setting her legs down. "So?" he asked, looking up at her from under his eyebrows.

She leaned forward in the chair. "So you should go get a flavored condom out of the drawer, but kiss me first."

Derek smiled a little, pleased, and did as he was told. Lydia could taste herself on his lips, and probably Erica too. She'd never been interested in knowing that someone else had been where she was—"sloppy seconds" was the revolting phrase Stiles liked to use—but in this thing the four of them were doing she found that she liked it quite a lot. It was comforting, somehow.

She sat back again, watching with interest as Derek walked away, and out of the corner of her eye realized that Erica had yet to complete her task. "I thought you were going to take care of Stiles?" Lydia asked.

Erica stirred, lazily, lifting her head up from where it lay on Stiles's thigh. "They wore me out," she said. "Besides, he wanted to watch without distractions."

Stiles, who was sitting with his back against the headboard, shrugged. "You bring your horse up to the starting line, you don't leave before you see how he does in the race."

"I'm not a _horse_ ," Derek said, rolling his eyes.

"Well, it's my birthday, and I want you to come," Lydia said.

"Don't have to twist my arm," Stiles said, and looked down at Erica. "You wanna do the thing? I'm like, a hair trigger here, and you're all floppy, so."

"Sure," Erica said, and rolled up on her hands and knees. One of them had already got the condom on—strawberry from pale pink tinge of it—and Erica licked her palm before wrapping her hand around the base of Stiles's cock.

"What thing?" Lydia asked.

"I think you'll — like it," Stiles said, his voice hitching when Erica spread her lips around his cock. "On my end, I mean, now that you have a cock. I don't think you'd be interested in being on her end."

"You like it both ways," Derek said, eyebrows raised, and he seemed to know what was about to happen.

Stiles smirked up at him. "So do you." By now Erica had worked her mouth part way down Stiles's cock, and was sliding back up again. "Ready?"

Erica gave him a thumbs-up.

"Cool, because this is going to be sooooo fast." He slid one big hand into her hair and used it to push her head down as he thrust up into her mouth.

"Oh," Lydia said, blinking. Stiles was right; she'd never been interested in the mouth-fucking business when it would be her mouth getting fucked. But picturing herself on the fucking end, she could see the appeal. Erica's lips were stretched wide, her eyes closed, and she was just taking what Stiles was giving. Lydia could imagine Stiles or Derek in that position, too, and wanted to put them there. 

Stiles had one of Erica's hands in his, and he'd only thrust a few times, really, before he was coming, gritting his teeth and grunting in that low way of his. He was right, it _was_ fast, and she was gratified that he'd been as into the lessons as she had been, as he was when she taught him directly. She'd have to use him as her proxy again if he liked it this much. Maybe on Erica, next time.

"Fuck," he said, panting, his cock slipping out of Erica's mouth. She crawled up to sit next to him, a big grin on her face. 

Stiles opened his eyes, and looked at Lydia. "Um, are you going to ..."

"Oh, yes," Lydia said, slipping down onto the cushion Derek had been using earlier.

She would have felt a little bad, leaving Derek literally hanging, but he'd been watching, too, and didn't seem to mind. He opened the condom—dark red, cherry, her favorite—and said, "Shall I?"

"Sure," she said, because it was always hot watching a man touch himself, knowing he was hard because of her. 

Derek then moved the chair to face sideways before sitting down.

"Bed's more comfortable," she said.

"Yeah, but you know they want to watch." He waved a hand at Stiles and Erica.

"Aw, thanks," Erica said. "So thoughtful."

Lydia raised an eyebrow at Erica, who responded with a saucy grin. Fine, if they wanted to watch, then Lydia would give them a fucking master class. After all, you couldn't get stupid high school boys to do your bidding if your technique was merely adequate.

She knew some women didn't like blow jobs and while she respected their stance she didn't _understand_ it. She loved the power of having her man at her mercy, making him come when it pleased her. Derek had more than earned his reward, too, so she wasn't inclined to make him wait any longer. But she also just loved the feel of it, the smell of him and the weight of his cock in her mouth, his fur-covered balls soft and dry against her fingers, the sound of his breathing and whimpers as he got closer. (True, the condom tasted like dusty hard candy but that was better than latex, or ejaculate for that matter.) And there was the thrill of just being surrounded by all that _maleness_ ; she loved those nights when Derek overwhelmed her with his strength, but also when he held back for her sake, which was its own sort of strength. She was attracted to men for a _reason_ , after all.

"Lydia," Derek moaned, brushing a thumb across her forehead. He was sweet to warn her, even if she didn't swallow, and she moved forward, taking as much of him into her mouth and throat as she could, her hand wrapped around the rest of his length. He bucked up into her shortly after that, moaning her name, hands gripping her shoulders, and she rode him out until he relaxed.

She sat back on her haunches, a little out of breath herself. Erica came up with a tissue to dispose of the condom. She and Stiles had been excellent helpers all day. 

"Come here," Derek said. "I feel like I haven't kissed you enough."

Stiles's head appeared, suddenly, as he leaned over off the bed. "There hasn't been enough kissing _generally_ , in my opinion. Everyone on the bed, Lydia?"

She smiled up at Derek. "Yes, let's do that."

They arranged themselves so that Erica and Lydia were in the middle, Derek spooning Lydia and Stiles on the other side of Erica, though his arms were so long he could easily reach Lydia too. There was a _lot_ of kissing then, and vague fondling, and giggling and sighing, and they went into that place they always seemed to enter when it was the four of them and the orgasms were behind them and it was just cozy and nice.

"Satisfied with your birthday?" Erica asked her.

Lydia reached down to entwine all four of their hands atop her hip, snuggled down deeper into Derek's arms, and looked up at Stiles and Erica. She felt warm and loved, which made her, well, generous. "Very satisfied," she replied. "Thanks to all of you. I suppose you're next, Erica?"

"Oh, Stiles and I have that _all_ worked out," Erica said.


	3. outside

Erica said: "I want a gang bang for my birthday."

Stiles, who was lying sort of on top of her on the couch, reached over his head to give her an encouraging fist bump. He already knew what she was going to say since most of what they did in their one-on-one time was talk about kinks and watch porn (what they could find that wasn't terrible) and get each other off; they did a _lot_ of sexting. He'd told her she should just ask for what she wanted, sometime when they were all together but not in bed, and when they were all doing their reading piled on top of each other on the couch felt like a safe time.

Derek, on the other end of the couch, raised his eyebrows. "You want other people with us?" he asked.

"No, we're enough," she replied. "Just, all of you on me at the same time. Three cocks and three holes is easy math but I'm flexible."

"Okay," Derek said, and went back to his book.

But Lydia wasn't going to be so easy. She was sitting in Derek's lap, her back against the arm of the couch. "What do you like about them?"

Erica forced herself to maintain eye contact because there _wasn't_ anything shameful about any of this, even if she was nervous. "Being the center of attention, like, everyone touching me and fucking me. In the videos they always talk about how hot she is and how much they want to fuck her, and how good she is to fuck, and they call her slutty and you know how I like that."

Lydia cocked her head. "So you want us to all fuck you at the same time and talk to each other about what a sweet pussy you have and how much you love it?"

"Pretty much?" Erica held her breath; Lydia could go either way on this one, she knew, but she _wanted_ it, had been thinking about it ever since Stiles had declared he wanted sex for his birthday and then Lydia did and it became a _thing_. They were already planning Derek's, because it was useless to ask him what he wanted; he'd always just say "whatever you guys want," which was not helpful.

"Well." Lydia absently tapped her fingers against Derek's knee. "None of us will say anything demeaning."

"Sure," Erica said.

"Then that's what we'll do," Lydia replied.

Erica grinned in relief. "Awesome. Thanks."

"Can we practice now?" Stiles asked.

"No," Derek said. "Finish your reading and maybe we can come up with something else, though."

"Seriously, you're going to do Lydia's reward sex thing too?" Stiles asked, making a face.

"Business before pleasure," Lydia said, and Erica snickered.

But a couple of hours later, when they'd all finished their work, Derek was as good as his word.

* * *

On the actual day, Erica slept in, went to her noon Music History class because she really liked it, and met up with Boyd and Isaac for lunch and general hanging-out that stretched out across the afternoon. 

When she did get to Derek's place, Lydia immediately directed her into the shower. Stiles was at the door with a robe when she got out, then led her into the bedroom.

"Get into the middle of the bed," he said.

As she did, she noticed the little differences in the room: all the pillows were gone, and the standing mirror had been moved to sit alongside the bed instead of in the corner. Derek and Lydia were standing near the nightstand, already undressed, and Lydia was wearing her strap-on. Derek was hard and had a bottle of lube in his hand.

"So, Erica, is this your first gang bang?" Stiles asked.

Erica smiled because it was cute how he was making it like the porn videos they'd watched. "Yeah, it is."

"Nervous?" He was quickly slipping out of his clothes and hey, he was hard, too.

"Nope, not at all."

Stiles raised his eyebrows. "Because you want it that bad?"

"Yeah," she said, and turned to Lydia and Derek. "And the people I'm going to do it with."

"Because we're hot?" he asked, grinning.

She laughed. "Sure, but also, because you're my favorite people."

"Erica! You can't bring feelings to the gang bang."

"Why not?" Derek asked. "It's her gang bang."

Stiles rolled his eyes. "Okay, take off the robe for me."

She flung it on the floor in front of the mirror.

"Wow," Stiles said. "You have beautiful—"

"I have beautiful everything," she said.

"Wanna prove that by spreading your legs for me?"

She did, proudly, because all three of the people staring at her had been very eagerly kissing her pussy within the last few days. 

"You're already wet, aren't you?" Stiles asked. "Been thinking about this all day?"

"So have all of you by the looks of it," she replied, grinning.

"Fine, get on your hands and knees and face the mirror," Stiles instructed.

She did, and now her behind was facing the other three, so she spread her legs a little and shook her ass. It was smacked of course--that was the point--by Derek. 

"Brat," he said, not unkindly, and Erica giggled. Her laugh turned to a moan when his lube-coated thumb slid into her, his big hand spread across her ass. She pushed back into him and their eyes met in the mirror. 

"So what is it about her ass?" Stiles asked him. His hand was on her, too, stroking her back and the curve of her waist. 

"How round it looks and feels in my hand," Derek replied, his clean hand palming her cheek and his thumb moving slowly in and out. 

"And around your dick?"

Derek gave him the "do I have to?" look and Stiles waved his hand in encouragement. "Tight," he said. "Hot and tight."

"You really have to open her up, huh?" Stiles asked. 

"Takes time to do things right," Derek said. He replaced his thumb with two well-lubed fingers and Erica shuddered, trying to both enjoy the feeling of being penetrated and take in Derek's words. "I don't mind, though. It's worth it."

"Don't have to do much to get this open," Stiles said, long fingers pushing unceremoniously into her pussy, and she wished she could lean into him and Derek at the same time. Then she realized she'd better get used to that feeling, at least today.

Lydia clicked her tongue. "Because she's a _woman_." She paused, then: "A woman who thinks about sex all day and is always ready for it."

"A slut?" Stiles asked, grinning.

"A slut for us," Lydia replied, her smaller hand replacing Stiles's on Erica's pussy, but she was no more gentle, and Erica wouldn't have wanted her to be. " _Our_ slut."

"Yeah, our slut," Derek said.

Stiles leaned forward and now his hand, slick with her own juices, was fondling her breast. Or really, groping selfishly, rolling a nipple between two fingers. A touch not meant for her, except in the ways that it was, and she thrilled to it. "Hear that, Erica? You say it."

She realized her mouth was dry, had been hanging open during all of this discussion of her. And it was a _lot_ , the talking and the touching and preparing. She swallowed. "Your slut."

"Again," Derek said.

"I'm your slut," Erica said, louder this time.

"You're going to come already, aren't you?" Stiles said.

Erica nodded. "Please."

"You should come as many times as you want to," Lydia said. "We'll keep count. So many orgasms for my slutty girlfriend."

"This first time, though," Stiles said, "you should make yourself come, I think."

Lydia nodded. "I agree," she said, and her hand was gone, moved to Erica's other breast.

"We've got you," Stiles said, and she realized they did—hands firm on her waist and hips, holding her up. 

So she picked up one hand and reached back between her legs, reaching for her pussy while the others took care of her nipples, her ass. It didn't take much, just a quick pinch of her clit—and forcing herself to watch them watch her in the mirror—before she came, shuddering, but still being held open by their hands. She'd never felt so exposed.

She loved it.

"That's one," Lydia said.

Derek nodded. "She's ready, anyway. We should probably fuck her now."

"Well," Stiles said. "Let's do that."

"Water first," Erica said, so Stiles handed her a bottle to sip on while the others arranged themselves and her. Derek lay down on his back, his condom-covered cock standing up straight. He and Stiles lifted her up and, surprisingly, put him in her pussy, not in the ass he usually preferred and had so carefully prepared. But it was a nice change, and for him, too, judging by the way he closed his eyes and hummed as he entered her. 

"How's that?" Stiles asked him.

"I forget how wet she is." Erica squirmed a little, squeezing around his dick, and he bit his lip. "Wet and fuckable."

"So much." Stiles put a hand on her back. "Bend over for me?" he asked, and as she did he copped another feel of her breasts. 

They weren't facing the mirror anymore, so she sensed rather than saw Lydia kneeling on the bed behind her. Lydia penetrated her slowly but steadily, trusting that Derek had done a good job preparing her. If she'd felt full before it was nothing like now, nothing like having both holes stretched and filled up and _taken_. She put her forehead down on Derek's furry chest, licked at his nipple just because it was there, and let herself just feel what she'd been fantasizing about for so long. Lydia's hands were stroking her back, soothing her, and Derek's fingers were in her hair.

"You okay?" he asked.

"So fucking okay," she replied, grinning into his skin.

"Ready for me?" Stiles asked from somewhere above her. "Or I can just fuck Derek's mouth, no problem."

Erica popped her head back up, and there was his cock, hard and pretty and in her face. "No, no, mine," she said, opening her mouth and reaching for it.

Stiles laughed. "Wow, you _are_ an eager slut, aren't you? We all want you to love this, so take my hand, squeeze it all you want, but if you don't like something you let go or pinch me or punch Derek in the chest, okay?"

"Got it, totally," Erica said, nodding and taking his hand. Stiles's little threat, empty though it was, had made her impatient. "Gimme."

He fed his cock to her, and they'd done this often enough that he knew how deep into her throat was comfortable for fucking and stopped there. He was wearing one of the orange condoms, Erica's favorite because they reminded her of kool-aid and flavor-ice. "Good?" he asked.

She squeezed his hand and blinked. That was it; every place that could have a cock did have a cock, except her hands, maybe, but she wanted those for other things anyway.

Stiles ducked around her to make eye contact with Derek. He wasn't straddling Derek's head but kneeling just behind it. "You all right? Good view?"

"Of Erica's lips stretched around your cock? Fuck yeah," Derek said. He was breathless, but then, they were all laying on top of him.

"Lyds? If you're good to go you can start us off."

"Okay," Lydia said, and her voice sounded strangely far away. She put her hands firmly on Erica's hips, and slowly started fucking her. The slow start was good, suited Erica at least, because she was still getting used to the feeling of all these cocks inside her. The boys were feeling their way, too, figuring out the rhythm. Stiles and Derek were holding her up, keeping her mouth at a good angle for Stiles's cock but also just taking her weight, so she relaxed into them, let her body go liquid, be pushed around by the three cocks and six hands. And those hands were definitely getting their gropes in, even as they held her up; the boys fondling her tits while Lydia's clever fingers had slipped between Erica and Derek. She'd found Erica's clit, to be sure, but she was also feeling Derek's dick move wetly in and out of Erica's pussy, something she liked to do.

"This is fucking amazing," Stiles said, grinning broadly at Erica, and she was glad to have pleased him as much as she was pleasing herself. Pleased Derek and Lydia too, apparently.

She was keeping her eyes on his face, when they were open, because it was just about the only thing that wasn't moving and getting her mouth fucked could make her a little dizzy. But she blinked at him, slowly, and he moved one hand moved from her breast to her cheek, stroking her gently.

"Love it," Derek said. "Love all of you on top of me."

"And that sweet pussy?" Stiles asked.

Derek chuckled a little, though he sounded breathless. And maybe it was a silly weird thing to say but Erica wanted to hear it, so she pinched his nipple.

"Ow! Okay, fine, Erica!" He cleared his throat and when he spoke again he purposely pitched his voice a little lower and spoke very slowly and deliberately. "Love fucking your hot, wet, sweet pussy. Feels so fucking good around my cock, so tight. That what you wanted?"

Erica hummed and stroked his nipple softly.

"Slutty _and_ demanding," Lydia said. "I approve."

"Good for you too, Lyds?" Stiles asked.

"I like seeing her face get fucked just as much as anyone else in this room," she said. "And I think I've finally found the right angle and resistance for my cock to actually hit my clit."

"Seriously?" Stiles asked, his eyes widening.

Erica could feel herself flushing all over to hear that—they'd tried a bunch of different positions, but of course not this one. It was like the last piece of the puzzle, knowing that Lydia was getting something special from all this, too. She wished she could move a little, push into her, but she had to settle for stroking Lydia's calf with her toes.

"Oh, sweetie, you like that?" Lydia said, stroking her side. "Your ass is so tight. Makes it easier to keep my cock steady against me. I've never fucked Erica's ass or either of you boys from behind. I guess that's the trick of it?"

"You think you can come from it?" Stiles asked.

"Yeah," Lydia said, and she thrust harder, more selfishly, which made Erica even hotter. "Yeah, I want to."

"Oh my god, Lydia, I can feel you," Derek said. 

"My hand on her clit, of course you can," Lydia said.

"No, I mean, your cock," Derek said. "I can feel it like, inside. I can feel it moving inside Erica, feel it against my cock."

"Jesus," Stiles said. "Fucking, I'm _so_ doing that next. Fuck."

Erica moaned, because fuck she was totally getting what she wanted. They were talking about her like she wasn't there, talking about her _body_ , fucking her for their pleasure, all of it, and she was a little overwhelmed by how good it felt, how much their words were getting to her. She didn't want to make a sound to interrupt them, but she just couldn't help herself.

"Want to come, sweetie?" Lydia asked, pushing against her clit.

The moan was more urgent then, because she did, she wanted to come when they were all inside her, and then have them keep fucking her after that, when she would be even more boneless and they could be even more selfish. Thinking about that, about everything that had been happening, might have made her come more than Lydia's fingers did, and she struggled not to clench too hard around any of the cocks inside her.

"That's two," Lydia said. "And I'm next." She put both hands back on Erica's hips and then started thrusting faster. Erica knew from experience how strong Lydia was, especially her legs, and now Lydia was pushing Erica forward into Stiles and down onto Derek with the force of her fucking.

"Keep that up," Derek said, "and I might come before you."

But it was Lydia who came first, shouting as though the orgasm had been torn out of her body. She slumped down onto Erica and the extra weight set Derek off, with Stiles not far behind. They slumped down onto the bed, panting, Erica and Lydia falling off on either side of Derek while Stiles toppled over across the head of the bed.

Erica grabbed the bottle of water she'd left on the side table. "We are so doing that again."

"Another day, or later tonight?" Lydia asked.

"As soon as I can get them hard again," she replied.

"Oh my god," Stiles said. "You weren't kidding about the gang bang thing." 

"Or the slut thing," she said. It was easy to grin now, and to ask; as accepting as her boyfriends and girlfriends were about all kinds of things, you never really knew. But it was cool to be able to say, I want to get fucked some more. She could wait out the refractory period. Lydia had always said it was good to be patient, so she was going to try. Within reason.

Derek was the first one off the bed. "I guess we can put off ordering the pizza." He took clean up duty, taking care of his own condom and Stiles's before helping Lydia out of her harness and carrying the dildo into the bathroom.

Now that Lydia was on her feet, too, she pulled her tablet out of her bag. "It's going to take you a while to get them going again," she said. "Why wait when we can order online? Eighteen inch pepperoni and mushroom with extra cheese. Large garden salad."

"Garlic knots!" Erica said.

"Garlic bread with cheese too!" Stiles said.

Derek walked back into the room. "Make sure there's a side of sauce. There's already stuff to drink in the fridge."

Erica and Stiles were sitting up now, backs against the wall behind the bed. Erica loved this part right after sex when they were all just wandering around naked and cozy and thinking about dinner or going to bed or whatever. She took Stiles's hand.

"All set. Forty minutes." Lydia set the tablet aside. "Now, since Derek likes to be on the bottom so much, I think we should put Erica on her back this time so he can have her ass and Stiles her pussy and I can sit on her face."

"I love you so much," Stiles said. 

"I know, sweetie," Lydia replied, but scooted over to get a kiss from him anyway. "Erica?"

"Let's do it. Just give me some lube so I can get these two going."

"I've got it," Derek said. "You might need some more, anyway."

Lydia waved her arms. "Okay all of you move down. I want to sit at the head of the bed and watch." And that was good; Lydia needed a break sometimes, if they went two or more rounds. She liked to have some space after, to watch them as she came back to herself. She might put a hand on an ankle or upper arm, but she was content to watch, and they were content to be watched. It felt like she was still with them, just in her own way. Erica suspected that Lydia had some high school ex who'd been all over her all the time, but whatever the reason, Erica was glad they could give Lydia space to have what she needed, too.

Erica lay in the middle of the bed with Derek on one side and Stiles on the other. "Shouldn't you be like, kneeling above me or something?" she asked.

"Nah," Stiles said, laying next to her. "We don't have to do everything like porn." He kissed her then, maybe to prove his point or just because he wanted to. You could never tell with Stiles and Erica didn't really care.

She felt Derek, soft and furry, curling beside her. "Roll up on your hip for me? And spread your legs."

Erica bent her top leg and Stiles took hold of it, spreading her open even more.

"You're so open," Derek said. "You're not going to need much."

Stiles looked over her shoulder. "Oh my god, you're like, gaping. Lydia, can you see?"

"Of course I can. I did that." She smiled at Erica, who smiled back.

"Derek's going to open you even more," Stiles said. "We'll need to take a picture, after."

"Please," Erica said, because she couldn't quite see it.

"Are you okay?" Derek asked, probing her gently with two lubed fingers. "Feeling sore?"

"Feel amazing. Lydia fucked me so good."

"Yeah she's pretty talented with her cock," Derek agreed.

"Fuck yeah, she is," Stiles said.

Lydia nodded her head. "Thank you."

Erica turned to Derek. "You fucked me good, too," she said.

"Thanks," Derek said, smiling a little, but his eyes darted away from hers. It was kind of hilarious the way he could be so dirty, but the second you praised him he got all shy. Proof he was as much of a weirdo as the rest of them, which to Erica was a good thing.

"I think I did okay, too," Stiles said.

"Practice makes fucking perfect," Erica replied. "Now, gimme some lube, Derek, so I can get you guys going."

"Yep." Derek squirted the lube onto Erica's palm and she rubbed her hands together to warm them, then put them on the boys' soft cocks. 

"You can put your fingers back if you want to," she said to him.

"Our slut's feeling empty?" Stiles asked. "Want my fingers, too?"

"You know I do," Erica replied, because his fingers were amazing. Sometimes they were all she wanted, all she needed.

It took a little arranging—Erica was still on her side but now Derek had her thigh in his hand, spreading her wide open for him and Stiles and for Lydia to see. She had their cocks firmly in hand, loving the feel of them slowly reacting to her. She couldn't reach their balls but that was okay; it was good to go a little slower for this part. Stiles's other hand was on her breast of course, because he couldn't stay away from them. She was rolling her head back and forth between their kisses, and they were sucking her neck, shoulders, whatever they could get their mouths on. 

Sometimes the boys kissed, and their fingers entangled between her legs, like they were using her to hold hands. She couldn't imagine having a three-way with two guys who weren't into each other as much as they were into her. But she was the focus now, and was getting literally manhandled in the best possible way. Plus Lydia was watching, which made the exhibitionist in Erica very excited. She wished she could do something to show off a little, but she was pinned in. Though maybe just directing them around her body was showing off enough.

"Like what you see?" Stiles asked her.

"You three are always pretty to watch, no matter what you're doing," Lydia said. She was stroking her pussy absently, more intent on watching than on getting off. "I love slutty Erica coming out and getting what she wants. She knows that."

"Yeah?" Derek asked.

"Sometimes when it's just the two of us, and I don't need to go again but she does, she just gets out the wand and gets herself off while I watch her. So yeah." She stroked Erica's ankle. "I love my slutty girlfriend who needs to come all the time. Do you need to come now?"

"Not yet," she replied, because she was loving the slow burn in her belly, the way they were all getting restarted. The cocks in her hands were nearly there now, but she wanted them rock hard and begging for it before they went again. "Condoms, though."

"I'll do it," Lydia said, and Erica could hear her getting them out of the nightstand. Lydia crawled across their legs, rolling the condoms on and giving Derek a squirt of lube as well. "Stiles won't need it."

"God, no," he said. "She's so fucking wet."

Derek nodded behind her. "So wet it's trickling into her ass."

"She's so good to fuck," Lydia said.

"Good with her hands, too," Stiles said, biting his lip.

Erica set in to prove that, stroking them firmly, with more purpose, and loving how impatient the boys were getting. Stiles, of course, always was, but Derek was shifting restlessly too. They only put up with it for a few minutes more.

Surprisingly it was Derek who broke first. "Erica, need to be inside you," he said, his voice shaking. 

"Make her come first," Lydia ordered. 

"No problem," Stiles said, his long fingers focusing on her g-spot while his thumb pressed down against her clit, hard, and that really was all it took.

"All right, that's three," Lydia said, hopping off the bed. "Come on, Derek, back where you were."

Derek lay on his back, holding his cock steady for Erica to sit down on. His cock was bigger than Lydia's but Erica was so open that she took him easily, more easily than she ever had. 

"Fuck," Derek said. "I should always fuck them after you."

"You get them ready and I'm happy to fuck them open," Lydia replied, shrugging.

Stiles moaned. "Oh my god, is that going to be a thing? Can we make that a thing?"

"This thing first," Lydia said. "Stay focused."

"Yeah, yeah, sorry," Stiles said, but Erica wasn't worried. She kind of liked his little digressions during sex. 

Erica leaned back against Derek, her head on his shoulder. They'd never really been in this position before, and she missed seeing his face, but she could feel his beard and all that chest hair against her skin, reassuring her that he was there and with her. His hands were on her sides, soothing, steadying her for Stiles.

Stiles climbed up on the foot of the bed, as Lydia had, and there was some leg arranging to do, bending Erica's back behind Derek's and out of the way. He was smiling down at her but as he slid his cock into her pussy he bit his lip. "Fuck, wetter than you've ever been. Thick."

"She has come three times, Stiles," Lydia said.

Stiles looked over his shoulder. "You joining, Lyds?"

"Not yet. Pizza's coming in a second anyways."

"Okay," Stiles said, and lay down on top of Erica, nuzzling her breasts. "Too heavy? I know _he_ likes it."

Erica shook her head. Maybe she liked the weight as much as Derek did; she always liked being on the bottom, anyway. 

"Don't even, Derek," Stiles said, which meant Derek had probably rolled his eyes at him. "You fucking love us all piled on top of you. Can't get enough of it."

"Just start fucking, Stiles," Derek said, with that edge in his voice he always got when Stiles was right but Derek didn't want to give him the satisfaction. If Erica had been in any other position, she would have been laughing.

The moment Stiles started thrusting the door buzzer rang. "That's the food," Lydia said, pulling on Erica's sundress. It was big on her, of course, which conveniently hid that she wasn't wearing anything under it. 

"You need any help?" Derek asked.

She cocked her head. "It's a pizza and a bag of bread," she said. "I'm pretty sure I can handle it. Besides, you're a little busy. I'll be right back." She smacked Stiles's ass as she left the room. 

"Imagine that pizza guy?" Stiles said. "Getting Lydia with her hair messy and smelling like sex and she just doesn't care? Wishing he'd ask her to join in? Fuck, we should role-play that. I'd totally be that pizza guy. Wouldn't you?"

Derek nodded.

"Or Erica. We could put her hair up in the hat, and you and me in the bedroom and she totally hears us? And Lydia is like, 'hey, I could use another girl, there's way too much testosterone in there.' Because you know that's something she would say."

"She would," Erica said. "We could take turns."

"Fuck yeah, Erica and me in the bedroom and Lydia just looks Derek up and down and pounces. Tells him that she's already fucked us once but we're like rabbits and need to go again and could Derek help her out?"

"Ooh, and he fucks us while she watches," Erica added. "And we're already fucked open, you'd like that, Derek."

"Yeah, but I like this too," Derek said. 

"Yeah, this is pretty awesome," Stiles agreed.

"Stiles," Derek asked, "is that—"

"My balls, yeah," he said, smirking. "They're like, totally smacking into yours."

They grinned at each other and kissed around her, and that was becoming a thing, that they were rutting against each other through her. She could feel their balls smacking into her, too, and the whole thing made her hot and itchy for the fucking.

"Can you feel me?" Derek asked. He was fucking her now, too, pushing in as Stiles pulled out. "Inside, I mean?"

"Fuck yeah," Stiles said, and now he was focusing on the matter at hand. "That is fucking amazing, oh my god, sorry, I am with you now."

"Better be," Derek said, and fucked Erica harder.

Lydia came back into the room then. "What did I miss?"

"Stiles's elaborate fantasy about being the pizza guy," Derek said.

"More role playing in our future, I guess," Lydia said. Then: "Oh my god, your balls are—"

"Yeah, we know," Stiles said. "Does it look hot? Get a picture so we can see?"

Lydia grabbed the tablet. "More like a video. Everyone be quiet."

They were careful not to moan, just to breathe, didn't even look at each other for fear of cracking up, so the video would stay anonymous just in case. But that was hot, too, to just hear their flesh crashing together with wet slaps and the creaking of the bed as they went at it.

"Got it," Lydia said. "You're going to love watching that." She pulled off the sundress. "Ready for me now?"

"Always ready," Stiles said, sitting up to make room for her.

Lydia straddled Erica and Derek. "I'll try to give you as good a view as Stiles did," she said.

"You already are," Derek said, stroking her ass.

She lowered her pussy into Erica's face. "No fingers, baby," she said. "Get me off with just your tongue."

Erica had done this before, and it helped that Lydia had taken her time, was all turned on and hot for it. Erica loved reaching up with her tongue, starting with little kitten licks before getting her lips and teeth involved, even her nose stroking the velvety pink folds. She liked the musk of the boys but Lydia always smelled so good, so sweet. 

"Need help holding steady?" Stiles asked. 

"I'm all right," Lydia said. Erica could feel her hands were holding onto Derek's sides. "Just like watching you fuck her up close."

"Yeah, gonna slow it down or I'm not going to last that much longer," he said. "She's so fucking wet."

Erica was trying to focus on Lydia's pussy, hot and wet above her, tasting so good, but there was so much happening with the fucking and now they were talking again like she wasn't there. She closed her eyes, tried not to use her teeth.

"Mmm, I'll get off soon," Lydia said. "She's good with her mouth."

"She is so fucking good with that mouth," Stiles agreed. "And Derek's so happy, he just gets to stare at your ass and we're all on top of him."

"He should make her come." Lydia turned her head. "Derek, it's your turn. Get your fingers up here."

If it was too much before, now she was in overdrive feeling Derek's thick fingers leaving her waist and brushing her clit just above where Stiles was fucking her.

"Oh my god that is hot, Derek's fingers just coming out of nowhere," Stiles said. "I'm totally going to fucking come, Lyds, please tell me you're close."

Lydia pushed her hips down a little more, which made it easier for Erica to latch onto her clit, suck it like a tiny cock, work it with the tip of her tongue. "So close," she said, dipping her head down. "Come on, Derek, get her off so she does the thing."

"On it," Derek said, and Erica felt him pulling on her clit a little, pinching it, and she came again. She hadn't even known she was that close, because there was so much other stuff going on. She did "the thing" as Lydia put it, her muscles clenching around the cocks inside her and her mouth sucking Lydia even harder.

"Oh god," Lydia said, shuddering, and Erica had her, had done her job. 

Stiles was speeding up and then slamming into her, shouting her name. He slumped down on top of Erica, pulling Lydia on top of _him_ , and it was probably that extra weight that pushed Derek over the edge, coming with a strangled cry.

They fell off to the sides again, more drained than they'd been last time. Erica did a mental check, tried to see if any of her body needed more, but no; she was sated. Also she was pretty sure if she wanted more sex Lydia would kill her. Hell, if she wanted more sex and then the food got cold _Stiles_ would probably kill her.

"I'm ready for pizza now," Erica said.

They ate naked on the bed because the sheets were a mess anyway. What was a little pizza sauce or vinaigrette? But first they took a picture of Erica's gaping, used holes—she got on all fours and thrust her ass into the camera, which was super hot to do—and looked at that and watched the video Lydia had taken while they ate. 

"Thank you for my birthday," Erica said. "That was awesome."

"Guess I should come up with something for my birthday," Derek said.

"Oh honey," Erica said, patting his knee, "we've got you covered." She gave him a peck on the cheek.

"Really?" he asked, and that was absolutely relief on his face. 

"Of course we do," Stiles said.

"We've got it all planned out," Lydia added, nodding. 

"Well, that's cool, I guess," Derek said, but he was smiling.


	4. last

Derek didn't vary his routine on his birthday. It was Friday, so a lighter day anyway, but he was a grad student now so he couldn't just skip class. He taught, held office hours, met with his advisor and made sure she didn't need anything for her current project. He talked to both of his sisters and his parents on the phone, went to the gym, let the other folks in the lab buy him a sandwich and a cupcake for lunch. 

But he was a little distracted all day, wondering what his girlfriends and boyfriend were planning for that evening. He was sure it would be something he wouldn't have thought to ask for. While he prided himself on knowing what his partners wanted (except for that whole cunnilingus business, but they all said that wasn't his fault) he wasn't so great at knowing what _he_ wanted. The four of them had tried so many new things over their spring birthdays, and he didn't feel like he'd fully absorbed the new sensations and possibilities before he was presented with more. 

Derek got back to his suite around five, and Lydia, Erica and Stiles were already there, in various stages of dress, clearly freshly showered. 

"Oh, are we going out?" Derek asked, seeing one of Lydia's club-going dresses hanging outside the bathroom door.

"Not exactly," Lydia said. "But you should shower. We put your clothes for tonight in the bathroom."

"Okay." On the inside of the bathroom door were his tightest jeans and Stiles's dark red t-shirt. Derek scrubbed up quickly and thoroughly (cleaning inside was becoming a habit, now that Lydia's strap-on was regularly a part of their sex equation) and trimmed his beard.

"Oh so much yes," Stiles said when Derek came out of the bathroom. He was perched on the back of the couch in the dark brown cargo pants that hugged his ass just so. But instead of his usual long-sleeved loose t-shirt he wore a fitted white tank. The pants sat low on his hips and with the shirt stopping at his waist and no underwear there was a good bit of skin showing, as well as that tempting line of hair leading down from his belly button.

Which meant they were absolutely staying in. They'd only just convinced Stiles to wear shirts that fit his shoulders and arms, but he was far too self-conscious to reveal all that skin in public. So Derek let himself look Stiles slowly up and down, showing his appreciation, and was rewarded with a blushing Stiles. Derek leaned back against the door frame and crossed his arms.

Stiles laughed at the display. "You're a dick," he said. "Don't stretch out my shirt."

Derek shrugged. "You're the one who gave it to me to wear," he said. "You must like it." But when Stiles gave him the finger, he couldn't keep up the nonchalance and started laughing, himself.

Lydia came out of the bedroom in the purple dress that had been hanging on the outside of the bathroom door. Her hair was in bouncy thick curls and she wore deep purple lipstick and eye makeup that made her eyes look very, very green. But she didn't have her heels on, didn't even have them in her hands. Derek wasn't sure how she managed to fit an hourglass figure and those legs on such a tiny frame, but it was all on display in the short, form-fitting, low-cut dress. "Erica, which one do you want?"

Erica walked out just behind her. "I'll take Derek," she said. "You know he doesn't like to sit in those jeans." She was in her beloved blue corset top and a black skirt that was absurdly short on her and flared out over her hips. Lydia took Stiles's hand and led him back into the bedroom.

Erica's hair was curly, too, in that way that flipped back from her face, and she had on a lot of red lipstick, which always made her happy. Derek liked the way it framed her smile, like the mascara and eyeliner and whatever else framed her eyes. 

He looked down at her hands, then realized what she was about to do. "Really?" he asked.

"You know you look hot as fuck in eyeliner," Erica said, "so stop fighting it." 

He rolled his eyes and huffed, but followed her into the kitchen and boosted her up on the counter, then stood in the V of her long legs. "I don't mind wearing it, but I forget and rub my eye and then Lydia gets annoyed." He put his hands on her thighs and caressed them, just because he could.

"Well, since we're home, we can just touch you up," she said. It wasn't actually eyeliner, like the liquid Erica literally painted onto her eyelids. On Derek they always used eye shadow, inky black in a little pot, and made thick smudgy lines with an angle brush. Erica wiped away the powder that fell onto his cheekbones. "Also," she said, holding up another pot with red something in it. 

"What's that?" Derek asked.

"Lip stain, and I promise, it's not gooey."

"Okay," he said, and relaxed his mouth. They'd put lip gloss on him once before going out and while it looked okay, he'd hated the heavy feel of it on his lips and the way the girls' hair kept sticking to it. The lip stain felt better, sort of like chap stick.

Erica leaned back slightly to inspect her work. "Nice," she said, pushing him back and hopping down.

Stiles and Lydia were back in the living room now. He'd gotten his own eyeliner application, and lip gloss too, because he didn't mind it. He looked hot as anything, and more suited to it than Derek felt he himself did, but the girls disagreed. The four of them stood in a little circle, the others staring at Derek, and he fidgeted and cleared his throat. "So … what are we doing?"

"We thought we'd give you a little show," Lydia said. "After you give us one."

"Oh," Derek said. "What—what do I have to do?"

"Just what you're doing now," Erica said, her hand on his hip. "Wearing tight clothing and looking adorably confused."

"Had your fill?" Lydia asked him.

"Yeah," Stiles said. "Go for it."

Lydia squatted in front of Derek and undid his fly, then Stiles and Erica helped to peel the fabric off him. Derek sighed in relief, stepping out of the tight jeans and kicking them behind him. Of course he wasn't wearing anything under them—couldn't; nothing would fit.

Erica cocked her head. "Why don't men wear shirts and no pants more often?" she asked.

"It feels weird," Stiles said, shrugging. "But it definitely looks hot, at least on Derek."

"Not as hot as no shirt," Lydia said, so off it came, too, and now they were all dressed and Derek was naked. Well, except for the eyeliner.

"Okay?" Derek said, after a few seconds passed with no one saying anything.

"Sorry, sorry," Lydia said. "Your body is distracting." She patted his chest. "That's why we don't let you wander around with no clothes as much as you might like to. But today, all the nudity is yours."

Derek smiled; it wasn't that it was a sex thing, just, he didn't like wearing more clothes than he needed to most of the time. He let Lydia lead him to the couch, where she curled up next to him.

"We made you an elderberry soda," Stiles said, handing him a glass with a bendy straw. "You know, with that Ikea stuff." 

"Thanks," Derek said. 

Erica and Stiles were standing in front of the TV; they'd moved the coffee table out of the way. "We were thinking," Erica said, "we keep going out dancing, and it's dumb. We get all dressed up and hot, when really, we've got all the hot we need right here."

"The music always sucks," Stiles said.

"Overpriced, watered down drinks," Lydia added, "and you're always paranoid that someone will kick us out and take our fake IDs."

"It happens!" Derek said.

"Anyway instead of dancing for you at a club," Erica continued, "why not just dance for you at home?"

"You're all going to dance for me?" Derek asked.

"They are," Lydia said. "I'm going to sit here with you and watch. Okay?"

"Very okay," Derek said, because they were right. It was never long after they got out someplace that Erica and Stiles were out on the floor, Derek and Lydia in a booth, with Derek's arm around Lydia to keep the creeps away. Erica and Stiles would come back and forth to the booth when they didn't like the songs, maybe get Derek or Lydia out for a moment or two, and then they'd all go home and fuck. This was simpler; he was naked already.

"Okay, music please," Erica said, and Stiles switched on his iPod which was hooked into the same speakers as the DVD player, somehow. 

Derek recognized the song from that Beyoncé album that got everyone so excited over the holiday break. Erica and Stiles started dancing, but it wasn't how they danced in the club. They had some sort of routine going, and Derek realized that they had _practiced_ this. It couldn't be a coincidence that when Beyoncé sang "never seen a booty like this" Erica stuck hers out for Stiles to smack, or that they were mouthing the lyrics at him as much as to each other. It could have been corny, but it was so generous, that they'd planned these things, that he couldn't help feeling pleased and loved.

When the song changed they started grinding up on each other, almost kissing before pulling away, the bulge in Stiles's trousers growing. Erica dropped down into a squat and spread her legs—and she wasn't wearing anything under her skirt. Derek mouth went dry and yes, he still felt loved but he also felt, well, something _else_.

_I just want to be the girl you like_

Erica slid her ass slowly up Stiles's legs, watching Derek as she did. Stiles had a hand on her hip, but he was staring at Derek, too. They'd teased Derek at the club a few times, dancing up on each other for his benefit, but this was beyond any of that, beyond even anything he'd fantasized about. His cock was getting harder, he knew, and he would have felt embarrassed or at least exposed, except that that was the whole point, that Erica and Stiles had put together a routine to get that reaction from him, so they might as well see it. And he got to stare openly, nothing surreptitious about it, no tamping down unwelcome jealousy or possessiveness because they were both his as much as he was theirs and they were each others' and anyway, this was for him. This was all for him.

Then the French part of the song started, and while Erica was mouthing it to Stiles, Lydia leaned over and whispered it into Derek's ear. He'd taken French; he didn't get every word but something about feminists loving sex. Which, he was fucking Lydia and Erica on a regular basis. He was well aware of this.

Stiles and Erica were kissing now, and when the song changed to something slower—Beyonce still singing about her ass and how they shouldn't take their eyes off it—Stiles walked Erica back against the wall. Erica unfastened his fly and Stiles boosted her up, let her wrap her legs around him, his biceps flexing with the effort. He could just see Stiles's cock, hard and—jesus, that was a condom, already on it. Erica sank down onto Stiles's cock easily, and then he was fucking her.

Lydia hadn't moved, her chin on his shoulder and her hand on his chest. She threw one leg over his, the other curled up between them, and he put a hand on her knee. She pulled him toward her with her other hand, firm on his shoulder.

"They're first because it's so easy to get them going," she said. "Pretty, aren't they?"

Derek nodded. His mouth was dry; he gulped his soda.

"You and I take a little longer." Her hand was stroking his chest, gently, her manicured toes brushing against his leg. "We need a warm up. You're always so patient with me."

"So are they," he replied, leaning into Lydia so as not to take his eyes away from Stiles's ass clenching in those tight pants, then pushing back out, or Erica's breasts nearly bouncing out of her top. "With both of us."

"But when it's just us, and we have all night?" This close, Derek could feel Lydia's breath against his ear as she spoke, like a little tickle to remind him to pay attention to her. "You take your time and take me apart with your hands and your mouth until I'm begging for it."

He wanted to close his eyes, think about that, about how Lydia would give up her precious control to him, sometimes, and he'd work to make it worth her while. And besides, he'd sort of let her down, before. "I'm better at that now," Derek replied, thinking of the lessons in cunnilingus Lydia gave him on her birthday.

"Hey," Lydia said, her hand coming up from his chest to his cheek and turning him to face her. "Maybe better, but you were damn good before. Got it?"

This close, Lydia's beauty could be overwhelming, even moreso when she was telling you how things were going to be. But her eyes were soft with affection. 

"Got it." He smiled a little and she did, too.

"God, you're pretty," she said, and surged forward to kiss him firmly. "Now back to them. You know how they get if you're not watching."

"How _they_ get?" Derek asked, smiling widely, but he did as he was told.

The music changed again to something faster about falling in love with your radio, which Derek thought probably should be Stiles and Erica's theme song. Stiles was really pounding Erica now and she was grinning, loving it. Derek had fucked her like that more than once, and the memory made him hotter, probably a little harder, too. 

Lydia's hand was back on his chest and she was whispering again. "After I've finally convinced you it's time to fuck you still go ... so ... slow." 

Her finger was circling his nipple and he was suddenly very aware of how close her thigh was to his cock. He set his glass down on the crate that served as a side table, and took her other hand in his, clasped on top of his shoulder.

"You really do like fucking us best after we've come, don't you? Then you can just put me where you want me, strong arms holding me down."

Stiles was close to coming; Derek could tell by the way he moved, how he'd lost the rhythm. Erica had probably come at least once already, because she could do that from fucking and also because she would have kicked Stiles to get him to make her come if she hadn't. 

"I've never known anyone like you, Derek. You make it so good to be on the bottom."

Stiles shouted then, pinning Erica to the wall and coming. Derek started, as if he could feel the orgasm in his body, too.

"Oh my god," Stiles said, panting and laughing a little. "Can you stand up? Because I'm not sure I can."

"Sure," Erica said, and Stiles pulled out of her and set her down. He pulled a tissue out of his pocket to take the condom off—and of course he was prepared; that was Lydia's touch, no doubt, to put a condom on him under his clothes. 

"All right, I'm tagging out," Stiles said, looking at Lydia. "You good?"

"Yes," Lydia said, "but we're moving onto the bed."

By the time they'd rearranged themselves, Erica and Lydia were sitting at the foot of the bed, while Stiles and Derek were sitting at the head. It reminded Derek of their first night together, only this time Stiles was behind him. Also Derek was naked.

Stiles had shed the cargo pants but kept the tank, which was soft against Derek's back. The lube was on the bed next to them, and it didn't take much imagination to know what Stiles was planning.

Stiles caught Derek glancing at the lube. "What?" he asked. "You _love_ my fingers. Don't even."

Erica had brought the iPod into the room with them and was setting up another playlist. 

"More Beyoncé?" Lydia asked. "Don't be obvious."

Erica rolled her eyes, but then began to mess with the iPod some more, so Lydia must have caught her out.

"Blow," Stiles explained to Derek. "You know, the song where she talks about how good it is to go down on her?"

"A little too on the nose," Lydia said. She knelt in front of Erica and began unfastening her corset top.

Erica lifted her arms out of the way, still messing with the playlist. "And you call me impatient. Hot for my body?"

"Shut up," Lydia said, which meant she was. She made short work of the top and threw it aside, then gathered up Erica's breasts in her hands.

"Okay, okay," Erica said, laughing, and tossed the iPod to Stiles.

As Beyonce and Lady Gaga sang something about telephones, Lydia pushed Erica back onto the bed and began to kiss and lick at her breasts. Erica took advantage of the position to unzip Lydia's dress, then flipped up the hem and slid her hands under Lydia's panties.

"They do not waste time," Stiles said, "and neither should I, probably. Okay, I think on your knees would be easiest."

Derek sat on his haunches, still watching the girls going at it. Lydia had let up long enough for Erica to get her dress off entirely, and now they were making out and groping everything within reach. He could hear, though not see, Stiles lubing up his fingers.

"Ready," Stiles said, putting a clean hand on Derek's hip while he slid a slick finger into his ass. 

Derek groaned and almost instinctively spread his legs and leaned forward, putting his hands on his knees.

"There you go," Stiles said, giving him another finger. "Yeah, you just keep watching them and listening to me and letting me take care of you."

Erica finally managed to get Lydia to sit still long enough to remove her panties. Derek could see how turned on she was, her labia flushed and wet below the small, perfectly-shaped thatch of red-gold curls. Erica's fingers went to it almost immediately, dipping in and out and then to her mouth for a taste.

Stiles shifted to kneel behind Derek, and now he spoke into Derek's ear much as Lydia had done. "I love how you taste, too," he said, and Derek shuddered. They always used condoms with the girls, but when it was just the two of them things were more ... flexible. "Licking you off my hand, or my cheek. Or when you come on me and lick yourself off my stomach and then kiss me, Jesus."

Lydia had Erica on all fours in front of her now, facing away, so she could divest Erica of her own black skirt. She put her face between Erica's legs and licked a stripe from her pussy up to her ass, and wiggled her tongue inside. Erica hummed and dropped her head down onto her forearms, pushing her ass even more into Lydia's face.

"Yeah, you've made us all ass-crazy," Stiles said. "Especially with the super cleaning thing." He withdrew his fingers and while Derek figured it was just a pause, he whimpered at the loss anyway. Stiles patted his flank with his clean hand. "It's okay, babe. I'm taking care of you, remember?" More lube then, and when the fingers came back there were three of them. Derek leaned into them, making Stiles chuckle.

Erica had pushed back up to her hands and was looking back through her legs at Lydia. "Gimme your pussy, goddamnit!" she shouted, annoyed.

Derek started laughing. He couldn't help it. This was his life now: watching his girlfriend go down on his other girlfriend, his boyfriend fucking his ass with three fingers, and he was laughing. Well, at least Stiles was laughing, too.

Lydia huffed. "Calm down," she said, and then in a move she'd clearly done before, she kicked her legs forward and shot them through Erica's legs. Erica grabbed Lydia's ankles and pulled, and Lydia flipped flat on her back on the bed, hands on Erica's ass. Erica spread Lydia's legs, bent them at the knee so her feet were flat on the bed, and then put her mouth on the pussy she'd demanded.

And as if that wasn't hot enough, watching the girls pleasuring each other, Stiles withdrew his hand again, spread some more lube on Derek's entrance, and went back in with four fingers. Derek gasped.

"Felt like it would fit," Stiles said, fucking him slowly and carefully. "Not that a pinky is really so much more. But I'm going to read up on fisting. Bet you'd love that."

Derek thought of Stiles's big hand inside him, up to the wrist or even further, and groaned.

"Thought so," Stiles said, and Derek could hear the smile in his voice. "Knuckles and everything inside you, and you so open, letting me take care of you like that. But now I can do this." He crooked his middle finger, stroking Derek's prostate.

"Stiles, I can't—"

"I know, babe," Stiles said, wrapping his clean hand around Derek's waist. "I'm not going to touch your cock, but you can any time you want, okay? I'll hold you steady so you won't need both hands. It's all up to you, and nothing else will stop or change."

Derek stilled. He liked being teased, but he'd learned from Kate that it was different when he put the power for when he came in someone else's hands. So he'd been cautious about letting his new lovers know. They figured it out anyway, of course, because that's what they did about everything else. 

"I can wait," he said. 

"Okay," Stiles said, kissing Derek's neck. "Then I'll just make you a little crazier."

Derek breathed through the spike and felt himself on a new plateau, between Stiles's fingers and the sight before him. The girls were humming and moaning, getting each other off with lips and tongues. Lydia was finger fucking Erica's ass, just like Stiles was doing to Derek, and he bit his lip to think about it. He wasn't sure how long they stayed in that pleasant place, feeling and watching and listening and _smelling_ —girls smelled so fucking good, always—but eventually Lydia grunted and began to buck up against Erica, who had to hold her still to finish her off. Lydia focused on Erica then, making her come quickly after that. 

Erica flopped down and rolled onto her back and stared up at Derek. "Fuck yeah." She was grinning, so Derek leaned down and kissed her. Stiles slid his fingers out, and Derek felt emptier, but not desperate. He waited for what was next, though he could guess. 

"You good, Lydia?" Stiles asked. "Need a break?"

She looked at Derek—or actually, at his cock—and shook her head. "Thanks for asking, but I had a nice slow start. Get a condom on so I can ride you."

"Yep," Stiles said, and jumped up to do so, because of course he was hard again.

"And we'll go wash our hands," she said, leading Stiles out of the room.

"Having a good time?" Erica asked.

"How is that even a question?" Derek replied.

"Just making sure." She rolled over onto her stomach. "Ready to get teased a little more? And I mean, seriously teased?"

His eyes widened. "You planned this!"

"Well, you planned for Stiles."

"With your help."

"And Stiles planned for me with your help, and now I planned this for you with their help."

Derek cocked his head. "What about Lydia?"

"Please. She planned for herself."

Lydia and Stiles came back into the bedroom, Stiles with the tank balled up in one hand. "Forgot I had it on," he said, and added it to the pile of clothing on the floor.

"How about the chair?" Lydia said, pointing to the dining chair that had ended up in the bedroom and was usually covered in clothes.

Stiles plonked the current pile onto the floor, then positioned the chair right at the foot of the bed, sideways, and sat down. Lydia climbed into his lap and his legs were so slender, and she so small, that there was just room for her knees on either side of him. She lowered herself onto his cock without any sort of preamble.

"Fuck," Stiles said. His hands were on her back, holding her securely she started to move up and down.

Erica was moving too, putting Derek where she wanted him—back against the wall, legs spread out in front of him. She leaned in for a kiss and he wondered how she still had her lipstick on, whether his own makeup was where it was supposed to be. Her mouth tasted of Lydia.

She sat down next to him, absent-mindedly stroking his chest. "Sometimes I think tits were made to bounce when we get fucked." She pulled at one of his nipples. "Did you like seeing mine bouncing?"

He nodded. "Almost came out of your top."

"But naked is good, too." Her hand moved to his other nipple. 

The iPod was still playing Beyoncé, though now more uptempo, and Lydia moved along with it. Her tits were seriously bouncing, because when she was on top she _went_ for it, holding nothing back. Stiles was solid under her, big hands holding her securely so she could move as she wished, kissing whatever his mouth could reach.

"I love how you love being touched," Erica said, her hand now stroking his abs, then moving lower, into the thicker hair just above his cock. "Stiles likes fucking and Lydia likes mouths but hands are your favorite, aren't they?"

"Yeah," he said, nodding. Her two hands had skipped to his thighs, short red nails scratching the skin. Then she shifted to sit between his legs and pushed up his calves to bend his knees. His muscles flexed at the light touch of her fingertips on the inside of his thighs. 

"Tip up your hips, that's right. Mmm, I love a man with his legs spread open. You can see everything, especially when your cock is being nice and staying out of the way."

Derek's cock lay against the crease between his thigh and his stomach, red and stiff and neglected. He was so hard now that he wasn't even thinking about it anymore. She already _knew_ , but he felt safe and wanted to _say_. "I like when you tease me because I can just feel."

"You should let us take care of you more often. We want to."

"Okay, I will," he said, because this was them taking care of him, just doing things they thought he might like, and it was nice, to not have to think about any of it for a while.

Erica bent down so her face was right up in his crotch. "Wow, Stiles really fucked you good, didn't he? Your ass is wide open and slick and red." One finger circled the rim of his hole and he shuddered. "Sensitive now, huh? Well, that part of you got enough attention anyway." 

She sat up slightly, leaning her head against his knee and wrapping her hand around it to keep herself steady. He put his hand over hers and she smiled at him. 

"I love nuts," she said, fondling them with one hand. "They're so soft and furry and vulnerable, sit so nicely in the palm of my hand. I could do this forever."

"You have before," Derek replied, and Erica giggled.

She glanced over her shoulder at Lydia and Stiles. "They're almost there, so it won't be long for you, either."

Stiles was gritting his teeth, a sure sign, and then he said, "Lydia, please."

"Yeah," Lydia said, moving her hand from his shoulder to her clit. "Do it."

"Fuck," he said, and pulled her down onto his dick, hard, and keeping her there while he thrust up into her, coming. She rode him, moaning and coming herself. Derek could almost feel the wet heat of her, the way her pussy would hug his cock. She didn't top Derek often but when she did she damn well knew what she was doing.

Erica waited for them to catch their breath, rolling Derek's balls gently in her hands all the while. "Anyone need a break?"

"Look at him," Lydia said, cocking her head. "How can we make him wait any longer when he's been so patient?"

"You never say that about me," Stiles said.

She turned back to him. "You're never patient."

"She's got you there," Erica said.

Stiles stuck out his tongue at her. "I'm definitely not now. I'm getting this condom off and then I'm getting all up in that business. Lydia, bed?"

"Please," she said, and he picked her up off his cock and set her on the foot of the bed. Erica reached over her head to the nightstand and grabbed a tissue for Stiles.

"What's happening now?" Derek asked.

Erica rolled off the bed onto her feet. "You're going to lie flat on the bed," she said, "and we're going to make you come. Oh, and keep those legs spread."

Derek raised his eyebrows. "Don't I need a—"

"No condoms for hand jobs," Lydia said. "Also you really need to stop trying to take care of us. It's your birthday."

He did as he was told, the thought of all of them with their hands on him making him shiver a little in anticipation. But he didn't want to be in his head now; he wanted to be in his body, wanted to feel all of it.

Stiles was crawling onto the bed, and Erica came back and when she nodded, well, it was kind of a free for all. At first it was hard to keep track of the six hands and three tongues that were roaming all over him. He couldn't decide if it was better to close his eyes and just feel, or keep them open and watch. They were all watching him, certainly, as they continued to tease, because none of those hands or tongues were on his cock. They were on his legs, his arms, his chest and stomach, in his hair and along his neck. He was pretty sure that was Erica's mouth around his balls, though, and he looked down and saw her head between his legs. So that was Stiles lifting one of his legs up to stroke that sensitive crease at the top of his thigh, and Lydia who was sitting on top of his chest, nibbling at his throat and grabbing hold of his arms. He could hear himself moaning, and twitched his free leg.

"All right, he's had enough," Erica said. "Let's do this."

Just like that, they all turned to his cock, and Erica gave it one good stroke with a hand that somehow had acquired a bit of lube. Then each of them put a hand on it, one above the other, like kids in a park grabbing a bat to decide who was up first. Stiles's hand was at the top, half on and half off to make room for both of the girls. 

"Okay, baby," she said. "Fuck up into us."

He did, and it was good, just enough room for some friction. Their free hands were back on him now, Erica's on his balls of course and Lydia and Stiles tweaking his nipples and kissing his neck and it was like they were just zeroing in on the important spots. 

"Head," he whispered, or maybe even just mouthed, but Stiles knew what to do. He wiped his top two fingers and thumb over the head of Derek's cock as he thrust up into them and it was _perfect_. "Oh fuck, I'm going to come. Oh fuck, I'm going to come."

"Come for us, Derek," Erica said, smiling up at him.

And with a couple final thrusts he was there, coming long and hard like he did after a good tease, his body going liquid and moving like a wave, hips still thrusting into their hands. He breathed for a second, thinking he was done, but then there was more, and he thrashed again, desperate, until finally he collapsed back onto the bed.

A warm wet cloth came from somewhere, wiping come from his stomach and lube from his ass, and presumably his lovers' hands. He was blinking, still a little out of it, and realized the music had ended. He heard Stiles speaking.

"Oh my god, Erica, I think you made him multi-orgasmic. I didn't know men could _do_ that." 

"I don't know," Lydia said. "It might have been just one long one, because of the come? But he's getting there."

"You all right, Derek?" Erica asked.

He sat up slightly and caught his reflection in the mirror near the foot of the bed. His makeup was smudged now, and he had lip prints all over his body from Erica and Lydia and even Stiles. He looked like some kind of debauched creature of the night, not the nerdy chemistry grad student he actually was. "Yeah, I'm good." He smiled and opened up his arms. "Come here."

Erica and Stiles got on either side of him, Lydia on top of his chest with Stiles and Erica's arms around her. He felt grounded now, and very loved. "Thank you," he said, and kissed the top of each of their heads.

"Just think," Stiles said, "now we have nine months to plan for next year!"

Lydia groaned but Erica laughed. 

"Stiles," Derek said, looking at him fondly, "let's just enjoy this moment, okay?"

Stiles looked up at him and Derek stroked his shoulder. It was difficult for Stiles, he knew—it had taken all evening to get _him_ there—but he could feel Stiles relaxing. "Okay," Stiles said, nodding.

Later, they would go into the kitchen and make Derek's favorite sausage pasta and salad, talking and laughing together all the while. But right now, this was good. They'd worked hard and they all deserved a nap. Derek watched them each as they nodded off, dozing against him, before he finally closed his eyes and slipped under.

**Author's Note:**

> You can find me on tumblr at [clio-jlh](http://clio-jlh.tumblr.com/).


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